Sunday, January 31, 2010
Taylor Reflection 31 JAN
the chapter focused on recognizing patterns and using formulas to find a specific part of the pattern
the types of patterns are
Arithmetic
Geometric
Neither
Arithmetic - is addition
Geometric - is multiplication
(division is considered Geometric because if a sequence divides it is considered to be a fraction.)
Then come the formulas to find a term:
Arithmetic:
tn-t'+(n-1)d
n=term #
t'=first term
d=what you add
tn=term#_in sequence
Geometric:
tn=t'∙r^(n-1)
r= what you multiply by
these formulas are used to find specific components of a pettern
its just a matter of memorizing what each variable of the formula represents and plugging in to solve.
What i dont understand comes along with the rest of what we learned
i think i am going to have a really hard time keeping track of which method to use on the test
if anyone has any tips for recognizing which lessons material to use that would be great
Dustin's Reflection
- First off you find the pattern. In this case we add by 2 each time.
- Now we find the info we need for the formula.
Reflection #24
Here's the two formulas:
1. Arithmetic- tn=t1+(n-1)d
n=term # t1=first term d=what you add
2. Geometric- tn=t1*r^(n-1)
r= what you multiply by n=term # t1=first term d=what you add
Ex.
6, 12, 24,.....
this is a Geometric sequence so you would use the formula tn=t1*r^(n-1)
then you would have 6*2^(n-1)
if you wanted to know the 4th term you would plug the 4 into the n and this is what you would get.
6*2^(4-1)
6*2^(3)
6*8
48
The only trouble I think I might have is remembering the formulas in this Chapter.
Chapter 13 Sequences and Recursive Definitions
There are two main types of sequences:
Arithmetic - where you add or subtract
Geometric - where you multiply
(*Note: division is considered Geometric. For example: If a sequence divides by three, it is considered to be multiplied by one-third.
Alicia's Reflection #24
There are 2 main types of sequences:
1.) Arithmetic- tn*t1+(n-1)d
n=term # t1=first term d=what you add
2.) Geometric- tn=t1*r^(n-1)
r= what you multiply by
Example: find the formula for the nth term of the arithmetic sequence
3,5,7
tn= 3+(n-1)(2)
tn=3+2n-2
tn=1+2n
Example: find the formula for the nth term of the sequence
3, 4.5, 6.75
divide the second term by the first to get your r.
4.5/3= 3/2 r= 3/2
tn=3(3/2)^n-1
I could use some help on the problems that ask you specifically to find the 200th term for example. I could also use some help with the recursive definitions. THANKSS!!!
Stephanie's Reflection
r = a+b sin theta
r = a+b cos theta
Cardioid
a-b sin theta
a-b cos theta
Rose
r = a sin n theta
r = a cos n theta
n is how many petals
Archimedes Spiral
r = a theta +b
Logarithmic Spiral
r=a^theta b
Converting
polar to rectangular
x=r cos theta
y=r sin theta
rectangular to polar
r=+/- sqrt x^2 + y^2
theta is (x/y)
Trig Chart:
0°
sin0=0
cos0=1
tan0=undefined
sec0=1
cot0=0
30°
sinπ/6=1/2
cosπ/6=√3/2
tanπ/6=√3/3
cscπ/6=2
secπ/6=2 √3/3
cotπ/6=√3
45°
sinπ/4=√2/2
cosπ/4=√2/2
tanπ/4=1
cscπ/4=√2
secπ/4=√2
cotπ/4=1
60°
sinπ/3=√3/2
cosπ/3=1/2
tanπ/3=√3
cscπ/3=2 √3/3
secπ/3=2
cotπ/3=√3/2
90°
sinπ/2=1
cosπ/2=0
tanπ/2=undefined
cscπ/2=1
secπ/2=undefined
cotπ/2=0
Saturday, January 30, 2010
Amy's Reflection #24
13-1
1. sequence-list of numbers
2. two main types: 1). arithmetic-add or subtract 2).geometric-multiply
Formulas:
1. arithmetic-used to find a term: tn . t1 + (n-1)d
**n=term #, t1=first term, d=what you add, tn=term #
2. geometric: tn=t1 . r^(n-1)
**r=what you multiply by..
Examples:
1. Find the formula for the nth term of the arithmetic sequence: 3,5,7,...
tn = 3 + (n-1) (2)
tn = 3 +2n - 2
tn = 1 + 2
2. Find the formula for the nth term of the sequence: 3,4.5,6.75,..
**divide the 2nd term by the 1st term to find r
4.5/3 = 3/2 = r
tn = 3 . (3/2)^(n-1)
13-2
Formula for a sequence that involves the previous term: (an - 1)
Examples:
1. Find the recursive definition of: 81, 27, 9,3,...
an = an - 1/3
2. 1, 2, 6, 24, 120, 720, ....
n = 1: 1
n= 2: 2
n = 3: 6
an = n . an - 1
13 -3
Series-List of added or subtracted numbers
**Leave it as a list: do NOT add
Formulas:
1. Arithmetic: Sn = n(t1 + t2)/2
**Finds the sum of the first n terms
2. Geometric: Sn = t1 (1 -r^n)/1-r
Examples:
1. Find the sum of the first 25 terms of the series: 11 + 14 + 17 + 20 + ....
Sn = n (t1 + tn)/2
t25 = 11 + (24)(3)
Sn = 25 (11 + 83)/2
= 1175
2. Find the sum of the first 10 terms of the series: 2-6 + 18 - 54 +...
**This is a geometric sequence and that is because you have to add or subtract the same number for it to be an arithmetic sequence, got it??
r = -6/2 = -3
Sn = t1(1 - r^n)/1-r
= 2(1 -(-3)^10)/1 - (-3)
= 2(-59048)/2
= -29524
so there you go..that's pretty much what we went over this week..and now for what i dont get: i really dont understand how to do problems like #3 on the quiz..i know im being little vague but all i remember is that i had no idea know to do it...so if anyone remember the question (which i doubt anyone does) can ya help me with that??
Thursday, January 28, 2010
Stephen's Reflection
The formula for arithmetic is tn=t1 + (n-1)d where n is the term number, t1 is the first term and d is what you add. For arithmetic, you will add or subtract numbers.
The other formula the the geometric formula. the formula for geometric is tn=t1-r^(n-1) where r is what you multiply by. For geometric formulas, you will multiply.
these are pretty easy formulas to remember but what i have problems with is finding the term numbers.
Wednesday, January 27, 2010
last week's blog
They are:
Sine and Cosine Sum/Difference Formulas:
cos(alpha+/-beta)=cos alpha cos beta-/+sin alpha sin beta )
sin(alpha+/- beta)=sin alpha cos beta +/-cos alpha sin beta
sin x+sin y=2sin(x+y/2)cos(x-y/2)
sin x-sin y=2cos(x+y/2)sin(x-y/2)
cos x+cos y= 2cos(x+y/2)cos(x-y/2)
cos x-cos y=-2sin(x+y/2)sin(x-y/2)
Tangent Sum/Difference Formulas:
tan(alpha+beta)=tan alpha+tan beta/1-tan alpha tan beta
tan alpha-beta=tan alpha-tan beta/1+tan alpha tan beta
Double-Angle/Half-Angle Formulas:
sin 2α=2sinα cosα
cos 2α=cos2α-sin2α=1-2sin2α=2cos2α-1
tan 2α=2tanα/1-tan2α
sin(α/2)=+/-√(1-cosα/2) cos(α/2)= +/-√(1+cosα/2)
tan(α/2)= +/-√(1-cosα/1+cosα)=sinα/1+cosα= 1-cosα/sinα)
Basics:
sin=y/r
cos=x/r
tan=y/x
cot=x/y
sec=r/x
csc=r/y
Trig Chart:
0°
sin0=0
cos0=1
tan0=undefined
sec0=1
cot0=0
30°
sinπ/6=1/2
cosπ/6=√3/2
tanπ/6=√3/3
cscπ/6=2
secπ/6=2 √3/3
cotπ/6=√3
45°
sinπ/4=√2/2
cosπ/4=√2/2
tanπ/4=1
cscπ/4=√2
secπ/4=√2
cotπ/4=1
60°
sinπ/3=√3/2
cosπ/3=1/2
tanπ/3=√3
cscπ/3=2 √3/3
secπ/3=2
cotπ/3=√3/2
90°
sinπ/2=1
cosπ/2=0
tanπ/2=undefined
cscπ/2=1
secπ/2=undefined
cotπ/2=0
Reciprocal Relationships:
cscΘ=1/sinΘ
secΘ=1/cosΘ
cotΘ=1/tanΘ
Relationships with Negatives:
sin -Θ= -sinΘ and cos -Θ= -cosΘ
csc -Θ= -cscΘ and sec -Θ= -secΘ
tan -Θ= -tanΘ and cot -Θ= -cotΘ
Pythagorean Relationships:
sin²Θ+cos²Θ=1
1+tan²Θ=sec²Θ
1+cot²Θ=csc²Θ
Cofunction Relationships:
sinΘ=cos(90°-Θ) and cosΘ=sin(90°-Θ)
tanΘ=cot(90°-Θ) and cotΘ=tan(90°-Θ)
secΘ=csc(90°-Θ) and cscΘ=sec(90°-Θ)
and for the most part I can work the majority of the problems, I just get myself a little lost every not and again. And I have problems with the ones that call for the use of chapter eight.
I get a little lost in translation of the formulas with the new formulas
so if anyone knows any tricks for these that would be great.
alaina's makeup blog
Here are the names and equations to know:
**Limacon
r=a+b sin(theta) r=a+b cos(theta)
**Cardioid
r= a+ or -bsin (theta) r= a+ or - bcos (theta)
**Rose Curve
r=a sin(n theta) r=a cos (n theta)
n=how many petals there are
**Archimedes Spiral
r=a (theta)+b
**Logarithmis Spiral
r=ab^(theta)
**Common circle with center point at the pole
r=a sin (theta) r=a cos(theta)
When converting to recangular, use....
x=r cos (theta) or y=r sin (theta)
When converting to polar, use...
r= + or - √x2 + y2
take the tan inverse....
theta= tan-1(y/x)
Tuesday, January 26, 2010
Polar Functions
Limacon - looks like a 'lima' bean
r=a+b sin(Θ)
r=a+b cos(Θ)
Cardioid - looks like a heart - (cardio as in cardiovascular)
a-b sin(Θ)
a-b cos(Θ)
Rose
r=a sin(nΘ)
r=a cos (nΘ)
To find n:
For number of petals = p
If p is odd, n=p
If p is even n=2p
Archimedes Spiral - The thing that looks really trippy when you make it black and white, and no, it's not moving.
r=aΘ+b
Logarithmic Spiral – Looks like a nautilus
r=aΘb
Monday, January 25, 2010
Taylor #twenty something blog
the two major things we focused on were memorizing graph shapes and their formulas and converting between rectangular and polar and viseversa
Graph shapes and their formulas
Limacon
r=a+b sin(theta)
r=a+b cos(theta)
Cardioid
a-b sin(theta)
a-b cos(theta)
Rose
r=a sin(n theta)
r=a cos (n theta)
(n=how many petals {if n isodd[#=n] if n is even [#=2n]}
Archimedes Spiral
r=a theta+b
Logarithmic Spiral
r=a^theta b
CONVERTING
when going from polar to rectangular you plug into
X=rcos(theta)
Y=rsin(theta)
and work out until you get a x point and a y point
when going from rectangular to polar you plug into
r=+/- squareroot X^2 +Y^2
and
Theta= (Y/X)
once youve solved for both of these you"ll plug into (+r, theta) (-r, theta)
the only thing i am having trouble with is the converting problems where the answers are already given and you have to solve for the things that were plugged into the equation to get the given answer
Sunday, January 24, 2010
Kane's Reflection
Limacon
r=a+b sin(theta)
r=a+b cos(theta)
Cardioid
a-b sin(theta)
r=a-b cos(theta)
Rose
r=a sin(n theta)
r=a cos (n theta)
n=how many petals
Archimedes Spiral
r=a theta+b
Logarithmic Spiral
r=a b^theta
Circle With Pole Center
r=c
Circle Intersecting Pole
r=a sin(theta)
r=a cos(theta)
I really just need to review over the notes and the chapter test. And memorize all the formulas of course.
Alicia's Reflection #23
Here are the names and equations to know:
**Limacon
r=a+b sin(theta) r=a+b cos(theta)
**Cardioid
r= a+ or -bsin (theta) r= a+ or - bcos (theta)
**Rose Curve
r=a sin(n theta) r=a cos (n theta)
n=how many petals there are
**Archimedes Spiral
r=a (theta)+b
**Logarithmis Spiral
r=ab^(theta)
**Common circle with center point at the pole
r=a sin (theta) r=a cos(theta)
When converting to recangular, use....
x=r cos (theta) or y=r sin (theta)
When converting to polar, use...
r= + or - squareroot of x^2 + y^2
take the tan inverse.... theta= tan-1(y/x)
CHAPTER TEST TUESDAY!!!! Goodluck :)
Amy's Reflection #23
Imaginary Numbers are no longer "imaginary"
Rectangular form: a + bi
Polar form: z = r cos theta + r sin theta i (abbreviated z = r cis theta)
Examples:
1. Express 2 cis 50degrees in rectangular form
2 cos 50 + 2 sin 50 i
2. Express -1-2i in polar form
radius = +- sqrt of ((-1)^2 + (-2)^2)) = +- sqrt of (5)
theta = tan^-1(-2/-1)
theta = tan^-1(1)
*tangent is positive in the first and third quadrants, 63.435 and 243.435
*63 is positive for cosine so it goes with the positive sqrt of 5
*243 is negative for cosine so it goes with the negative sqrt of 5
z= sqrt of 5 cis 63.435
z= sqrt of 5 cos 63.435 + sqrt of 5 sin 63.435 i
z= negative sqrt of 5 cis 243.435
z= negative sqrt of 5 cos 243.435 + negative sqrt of 5 sin 243.435 i
De Moivre's Theorem: z^n = r^n cis(n)(theta)
Examples:
1. z=2cis20degrees Find z^2
z^2=2^2cis2(20degrees)
z^2=4cis40degrees
2. 4cis15degrees Find z^4
z^4=4^4cis4(15degrees)
z^4=256cis60degrees
Limacon
r=a+b sin(theta)
r=a+b cos(theta)
Cardioid
a-b sin(theta)
r=a-b cos(theta)
Rose
r=a sin(n theta)
r=a cos (n theta)
*n=how many petals
Archimedes Spiral
r=a theta+b
Logarithmic Spiral
r=a b^theta
Examples:
1. r=theta+2
2. r=2+3cos(theta)
3. r=5
4. r=3sin(4 theta)
5. r=1/2(3^theta)
6. r=2sin(theta)
1. archimedes spiral
2. limacon
3. circle with its center at the pole
4. rose with 4 petals
5. logarithmic spiral
6. circle that intersects with the pole
ok what i really dont understand is the first two sections..if someone could explain them to me that would be awesome..thanks..
Stephanie's Reflection
r=a+b sin(theta)
r=a+b cos(theta)
Cardioid
a-b sin(theta)
r=a-b cos(theta)
Rose
r=a sin(n theta)
r=a cos (n theta)
n=how many petals
Archimedes Spiral
r=a theta+b
Logarithmic Spiral
r=a b^theta
Circle With Pole Center
r=c
Circle Intersecting Pole
r=a sin(theta)
r=a cos(theta)
1. Sine and Cosine Sum/Difference Formulas
- cos(alpha+/-beta)=cos alpha cos beta-/+sin alpha sin beta )
- sin(alpha+/- beta)=sin alpha cos beta +/-cos alpha sin beta
- sin x+sin y=2sin(x+y/2)cos(x-y/2)
- sin x-sin y=2cos(x+y/2)sin(x-y/2)
- cos x+cos y= 2cos(x+y/2)cos(x-y/2)
- cos x-cos y=-2sin(x+y/2)sin(x-y/2)
2. Tangent Sum/Difference Formulas
- tan(alpha+beta)=tan alpha+tan beta/1-tan alpha tan beta
- tan alpha-beta=tan alpha-tan beta/1+tan alpha tan beta
3. Double-Angle/Half-Angle Formulas
sin 2 alpha=2sin alpha cos alpha
- cos 2 alpha=cos^2 alpha-sin^2 alpha=1-2sin^2 alpha=2cos^2 alpha-1
- tan 2 alpha=2tan alpha/1-tan^2 alpha
- sin(alpha/2)=+/-sqrt(1-cos alpha/2) cos(alpha/2)= +- sqrt(1+cos alpha/2)
- tan(alpha/2)= +- sqrt(1-cos alpha/1+cos alpha)=sin alpha/1+cos alpha= 1-cos alpha/sin alpha
if you have a decimal, us the half-angle formulas for alpha and then multiply the decimal angle by two
Reflection #23
Heres the Formulas:
Limacon:r=a+b sin(theta) OR r=a+b cos(theta)
Cardioid:a-b sin(theta) OR r=a-b cos(theta)
Rose:r=a sin(n theta) OR r=a cos (n theta)
n=how many petals
Archimedes spiral:r=a theta+b
Logarithmic spiral:r=a b^theta
Circle with its center at the pole:r=c
Circle that intersects with the pole:r=a sin(theta) OR r=a cos(theta)
The thing I forgot how to do was go from Polar to Rectangular and Rectangular to Polar.
Tuesday, January 19, 2010
Stephen's Reflection
The sum and difference formula for sin is sin(a +/- b)=sin(a)cos(b)+/-cos(a)sin(b)
The formula for cos is cos(a +/- b)=cos(a)cos(b) -/+ sin(a)sin(b). The sign for cos will be opposite in teh parentheses which means if it is a - b then you will end up adding the cos and sin.
the sum and difference formula for tan is tan(a +/- b)=tan(a) +/- tan(b)/1 -/+ tan(a)tan(b)
The only thing i dont understand in this section is using the formulas with fractions with different denominators.
Monday, January 18, 2010
Taylor Reflection #22
they are
Sine and Cosine Sum/Difference Formulas
cos(alpha+/-beta)=cos alpha cos beta-/+sin alpha sin beta )
sin(alpha+/- beta)=sin alpha cos beta +/-cos alpha sin beta
sin x+sin y=2sin(x+y/2)cos(x-y/2)
sin x-sin y=2cos(x+y/2)sin(x-y/2)
cos x+cos y= 2cos(x+y/2)cos(x-y/2)
cos x-cos y=-2sin(x+y/2)sin(x-y/2)
Tangent Sum/Difference Formulas
tan(alpha+beta)=tan alpha+tan beta/1-tan alpha tan beta
tan alpha-beta=tan alpha-tan beta/1+tan alpha tan beta
Double-Angle/Half-Angle Formulas
sin 2 alpha=2sin alpha cos alpha
cos 2 alpha=cos^2 alpha-sin^2 alpha=1-2sin^2 alpha=2cos^2 alpha-1
tan 2 alpha=2tan alpha/1-tan^2 alpha
sin(alpha/2)=+/-sqrt(1-cos alpha/2) cos(alpha/2)= +- sqrt(1+cos alpha/2)
tan(alpha/2)= +- sqrt(1-cos alpha/1+cos alpha)=sin alpha/1+cos alpha= 1-cos alpha/sin alpha\
sin=y/r
cos=x/r
tan=y/x
cot=x/y
sec=r/x
csc=r/y
Trig Chart:
0°
sin0=0
cos0=1
tan0=undefined
sec0=1
cot0=0
30°
sinπ/6=1/2
cosπ/6=√3/2
tanπ/6=√3/3
cscπ/6=2
secπ/6=2 √3/3
cotπ/6=√3
45°
sinπ/4=√2/2
cosπ/4=√2/2
tanπ/4=1
cscπ/4=√2
secπ/4=√2
cotπ/4=1
60°
sinπ/3=√3/2
cosπ/3=1/2
tanπ/3=√3
cscπ/3=2 √3/3
secπ/3=2
cotπ/3=√3/2
90°
sinπ/2=1
cosπ/2=0
tanπ/2=undefined
cscπ/2=1
secπ/2=undefined
cotπ/2=0
Reciprocal Relationships:
cscΘ=1/sinΘ
secΘ=1/cosΘ
cotΘ=1/tanΘ
Relationships with Negatives:
sin -Θ= -sinΘ and cos -Θ= -cosΘ
csc -Θ= -cscΘ and sec -Θ= -secΘ
tan -Θ= -tanΘ and cot -Θ= -cotΘ
Pythagorean Relationships:
sin²Θ+cos²Θ=1
1+tan²Θ=sec²Θ
1+cot²Θ=csc²Θ
Cofunction Relationships:
sinΘ=cos(90°-Θ) and cosΘ=sin(90°-Θ)
tanΘ=cot(90°-Θ) and cotΘ=tan(90°-Θ)
secΘ=csc(90°-Θ) and cscΘ=sec(90°-Θ)
and for the most part i can work the equations
the two types of equations i am having trouble with are
A: the ones where is asks you to find something when it is _<_<_
and
B: the ones where it calls for the use of the chapter eight
i get a little lost in translation of the formulas with the new formulas
so if anyone knows any tricks for these that would be great
Alicia's Reflection #22
Ex: Find the exact value of 2sin15cos15
=sin2a
=sin2(15)
=sin30
=1/2
Ex: Find the exact value of sin 15
alpha=45 beta=30
sin(45-30)=sin 45 cos 30- cos 45 sin 30
sin 15= (squareroot of 2/2) (squareroot of 3/2)-(squareroot of 2/2)(1/2)
sin 15= squareroot of 6 - squareroot of 2/4
Ex: Find the exact value of cos 75
alpha = 45 beta = 30
cos(a + b) = cos(a)cos(b)-sin(a)sin(b)
cos 75 = (squareroot of 2/2)(squareroot of 3/2) - (squareroot of 2/2)(1/2)
cos 75 = (squareroot of 6 - squareroot of 2)/4
okay so study all the formulas and it should be pretty easy if you know the formulas, trig chart, and unit circle. GOODLUCK everyone!!!
Sunday, January 17, 2010
Amy's Reflection #22
Example 1: Find the exact value of sin 80 cos 130+ cos 80 sin 130
Let alpha = 80 and beta = 130 then sin 80 cos 130 + cos 80sin 130 = sin alpha cos beta + cos alpha sin b
= sin (alpha + beta)
= sin (80+130)
= sin (210)
= sin (180 + 30)
= - sin 30
= -1/2
Example 2: Find the exact value of
cos^215 - sin^215 = cos(2alpha)
= cos(30)
= sqrt 3/2
Example 3: cos 15
alpha = 45, beta = 30
cos (alpha - beta) = cos 45 cos30 + sin45 sin 30
cos (45 - 30) = (√(2/2) (√(3/2) + (√(2/2) (1/2)
= √(√6 + √2)/all over 4
Example 4: (1 + cot^2) (1 - cos 2x)
(csc^2x) (1-cos2x)
(csc^2x) (1-(1 - 2sin^2x)
(1/sin^2x) (2sin^2x)
= 2
Example 4: Find the exact value of sin22.5
alpha=2(22.5)
alpha=45
**if you are given an angle with a decimal you use the half-angle formula. To find alpha, you multiply by two.
Example 5: Sum Formula for Cosine
cos 75 cos 15 + sin 75 sin 15
=cos (75-15) = cos 60 = 1/2
Example 6: Find the exact value of tan15 +tan30/1-tan15 (tan30)
= tan(15 + 30)
= tan(45)
= 1
alrighty then, i hope that's enough examples to help someone out..ok what i need help with is the problems you gotta make a triangle and some how suppose to figure it out..so thanks to whoever can help me out with that..
Stephanie's Reflection
- cos(alpha+/-beta)=cos alpha cos beta-/+sin alpha sin beta )
- sin(alpha+/- beta)=sin alpha cos beta +/-cos alpha sin beta
- sin x+sin y=2sin(x+y/2)cos(x-y/2)
- sin x-sin y=2cos(x+y/2)sin(x-y/2)
- cos x+cos y= 2cos(x+y/2)cos(x-y/2)
- cos x-cos y=-2sin(x+y/2)sin(x-y/2)
2. Tangent Sum/Difference Formulas
- tan(alpha+beta)=tan alpha+tan beta/1-tan alpha tan beta
- tan alpha-beta=tan alpha-tan beta/1+tan alpha tan beta
3. Double-Angle/Half-Angle Formulas
sin 2 alpha=2sin alpha cos alpha
- cos 2 alpha=cos^2 alpha-sin^2 alpha=1-2sin^2 alpha=2cos^2 alpha-1
- tan 2 alpha=2tan alpha/1-tan^2 alpha
- sin(alpha/2)=+/-sqrt(1-cos alpha/2) cos(alpha/2)= +- sqrt(1+cos alpha/2)
- tan(alpha/2)= +- sqrt(1-cos alpha/1+cos alpha)=sin alpha/1+cos alpha= 1-cos alpha/sin alpha
if you have a decimal, us the half-angle formulas for alpha and then multiply the decimal angle by two
Reflection #22
10-3
Double-angle and half-angle formulas
sin 2(alpha) = 2sin(alpha)cos(alpha)
cos 2(alpha) = cos^2(alpha)-sin^2(alpha)=1-2sin^2(alpha)=2cos^2(alpha)-1
tan 2(alpha) = 2tan(alpha)/1-tan^2(alpha)
sin(alpha/2)= +- √(1-cos(alpha)/2) cos(alpha/2)= +- √(1+cos(alpha)/2)
tan(alpha/2)= +- √(1-cos(alpha)/1+cos(alpha))=sin(alpha)/1+cos(alpha)= 1-cos(alpha)/sin(alpha)
For a Decimal:use the half-angle formula to find alpha then multiply the decimal angle by 2.
One thing I don't really understand, and it seems like a lot of people don't understand this is knowing when to use the double and half angle formula.
Monday, January 11, 2010
Stephen's Reflection
Double angle formulas for sin2(a):
2sin(a)cos(a)
Half angle formulas for sin(a/2):
+/- square root of (1-cos(a)/2)
Double angle formulas for cos2a:
cos^2a-sin^2a, 1-2sin^2a, 2cos^2a-1
Half angle formulas for cosa/2:
+/- square root 1+cosa/2
Double angle formulas for tan2a:
2tana/1-tan^2a
Half angle formulas for tana/2:
+/- square root of 1-cosa/1+cosa, sina/1+cosa, 1-cosa/sina
Those are the formulas for db and half angles for sin, cos, and tan. the thing i dont understand is solving them in a problem.
Stephanie's Reflection
1. Sine and Cosine Sum/Difference Formulas
- cos(alpha+/-beta)=cos alpha cos beta-/+sin alpha sin beta )
- sin(alpha+/- beta)=sin alpha cos beta +/-cos alpha sin beta
- sin x+sin y=2sin(x+y/2)cos(x-y/2)
- sin x-sin y=2cos(x+y/2)sin(x-y/2)
- cos x+cos y= 2cos(x+y/2)cos(x-y/2)
- cos x-cos y=-2sin(x+y/2)sin(x-y/2)
2. Tangent Sum/Difference Formulas
- tan(alpha+beta)=tan alpha+tan beta/1-tan alpha tan beta
- tan alpha-beta=tan alpha-tan beta/1+tan alpha tan beta
3. Double-Angle/Half-Angle Formulas
sin 2 alpha=2sin alpha cos alpha
- cos 2 alpha=cos^2 alpha-sin^2 alpha=1-2sin^2 alpha=2cos^2 alpha-1
- tan 2 alpha=2tan alpha/1-tan^2 alpha
- sin(alpha/2)=+/-sqrt(1-cos alpha/2) cos(alpha/2)= +- sqrt(1+cos alpha/2)
- tan(alpha/2)= +- sqrt(1-cos alpha/1+cos alpha)=sin alpha/1+cos alpha= 1-cos alpha/sin alpha
if you have a decimal, us the half-angle formulas for alpha and then multiply the decimal angle by two
Alicia's Reflection #21
10-1
**Sum and difference formulas for cosine and sine:
cos (alpha + or - beta) = cos(alpha)cos(beta) - or + sin(alpha)sin(beta)
sin (alpha + or - beta) = sin(alpha)cos(beta) + or - cos(alpha)sin(beta)
**Use these formuals to rewrite a sum or difference as a product:
sin(x) + sin(y) = 2sin(x+y/2)cos(x-y/2)
sin(x) - sin(y) = 2cos(x+y/2)sin(x-y/2)
cos(x) + cos(y) = 2cos(x+y/2)cos(x-y/2)
cos(x) - cos(y) = -2sin(x+y/2)sin(x-y/2)
10-2
**Sum and difference formulas for tangent:
tan(alpha) + (beta)= tan (alpha) + tan (beta)/ 1-tan (alpha) tan (beta)
tan (alpha) - (beta)=tan (alpha) - tan (beta)/ 1+ tan (alpha) tan (beta)
10-3
**Double-angle and half-angle formulas
sin 2(alpha) = 2sin(alpha)cos(alpha)
cos 2(alpha) = cos^2(alpha)-sin^2(alpha)=1-2sin^2(alpha)=2cos^2(alpha)-1
tan 2(alpha) = 2tan(alpha)/1-tan^2(alpha)
sin(alpha/2)= +- squareroot(1-cos(alpha)/2) cos(alpha/2)= +- sqrt(1+cos(alpha)/2)
tan(alpha/2)= +- squareroot(1-cos(alpha)/1+cos(alpha))=sin(alpha)/1+cos(alpha)=
1-cos(alpha)/sin(alpha)
**Decimal- use half-angle formula to find alpha. multiply the decimal angle by 2.
I am having trouble knowing when to use what double or half angle formula. I have no clue which one to use because there are soo many similar ones. So if anyone can help me with that i would be happy! I also have trouble doing the problems when you have to make a triangle to find the angle for cos or sine. I dont understand what numbers go on the triangle, which quad the triangle goes in, and what side of the triangle the numbers go on.
Taylor Reflection #21
the formulas i solve and use well are the
Sum and Difference formulas for Cosine and Sine:
cos (alpha + or - beta) = cos(alpha)cos(beta) - or + sin(alpha)sin(beta)
sin (alpha + or - beta) = sin(alpha)cos(beta) + or - cos(alpha)sin(beta)
and
Rewriting a Sum or Difference as a Product:
sin(x) + sin(y) = 2sin(x+y/2)cos(x-y/2)
sin(x) - sin(y) = 2cos(x+y/2)sin(x-y/2)
cos(x) + cos(y) = 2cos(x+y/2)
cos(x-y/2)cos(x) - cos(y) = -2sin(x+y/2)sin(x-y/2)
the one type of problem that i really need help with are the ones that say solve for an equation when equal to _<_<_
if someone could please please explain how to work problem like this and possibly give an example that would be so great.
Alaina's reflection
thanksss
Sunday, January 10, 2010
Refection #21 I Think
Tan (α + β)=tan α + tan β/1-tan α tan β
Tan (α - β)=tan α - tan β/1+tan α tan β
Say you get tan 15degrees
You would use two angles from the trig chart that add or subtract to get 15 degrees (45 and 30). You plug them into the α & β parts of the problem then solve it. So here is what you would get.
Tan (45 - 30)=tan 45 - tan 30/1+tan 45 tan 30
=tan √2/2- tan√3/3 /1+tan √2/2 tan√3/3
=3(√3-3)/3(√3+3)
=(√3-3)/(√3+3)
The only thing I really dont understand from this week is the four random formulas we wrote down but never used.
Sin x + sin y= 2 sin x + y/2 cos x-y/2
Sin x - sin y= 2 cos x + y/2 sin x-y/2
Cos x + cos y= 2 cos x + y/2 cos x-y/2
Cos x - cos y= 2 sin x + y/2 sin x-y/2
What is this????
Amy's Reflection #21
Sum and Difference formulas for Cosine and Sine:
cos (alpha + or - beta) = cos(alpha)cos(beta) - or + sin(alpha)sin(beta)
sin (alpha + or - beta) = sin(alpha)cos(beta) + or - cos(alpha)sin(beta)
Rewriting a Sum or Difference as a Product:
sin(x) + sin(y) = 2sin(x+y/2)cos(x-y/2)
sin(x) - sin(y) = 2cos(x+y/2)sin(x-y/2)
cos(x) + cos(y) = 2cos(x+y/2)cos(x-y/2)
cos(x) - cos(y) = -2sin(x+y/2)sin(x-y/2)
**we didn't use these formulas for anything..so i got no idea where to use them..
Half-Angle and Double Angle Formulas:
sin(2alpha) = 2sin(alpha)cos(alpha)
cos(2alpha) = cos^2(alpha)-sin^2(alpha)=1-2sin^2(alpha)=2cos^2
(alpha)-1
tan(2alpha) = 2tan(alpha)/1-tan^2(alpha)
sin(alpha/2)= +- sqrt(1-cos(alpha)/2)
cos(alpha/2)= +- sqrt(1+cos(alpha)/2)
tan(alpha/2)= +- sqrt(1-cos(alpha)/1+cos(alpha))=sin(alpha)/1+cos
(alpha)=1-cos(alpha)/sin(alpha)
now here are some examples:
1. tan α = 2 and tan β=1, find tan (α - β)
= tan α + tan β/1-tan α tan β
=2+1/1-(2)(6)
=3/-1
=-3
2. Find the exact value of: tan 15+tan 30/1-tan 15 tan 30
tan α = 2 and tan β=1
find tan (α - β)
= tan (15 + 30)
=tan (45)
=1
3. Find the exact value of sin 15degrees
*exact value means you use your trig chart
*think of two numbers from the trig chart can either add or subtract to give you 15
*since it's (45-30), you would look for the formula that uses sin
sin (a-B) = sin a cos B - cos a sin B
* plug #s into equation..
a=45 degrees B=30 degrees
sin (45-30) = sin 45 cos 30 - cos 45 sin 30
sin (a-B) = sin a cos B - cos a sin B
sin (45-30) = sin 45 cos 30 - cos 45 sin 30
sin 15 = (square root of 2 over 2)(square root of 3 over 2) - (square root of 2 over 2)(1/2)
sin 15 degrees = (square root of 6 over 4) - (square root of 2 over 4)
= square root of 6 - square root of 2 all over 4
and peole remember we wont be allowed to use a calc. with trig functions so you might wanna pick up one that doesnt so ya add wrong on the upcoming test...ok i need help in is the last section..can someone explain 10-4 to me?
What is a Trigonometric Function?

Wednesday, January 6, 2010
Stephen's reflection
logb MN = logb M + logb N
logb M/N = logb M - logb N
logb M^K = K logb M
logb b^k = k
b^logb^k = k
Changing Bases: (Done when you can't solve a log)
Rewrite it as an exponential
Take the log of both sides
Move the variable to the front
then solve
Example:
log5 10 = x
5^x = 10
log 5^x = log 10
x log 5 = 1
x = 1/log 5
And there is still something i dont understand which is conics like formulas for circles and ellipses and stuff like that. sooo yea...
Monday, January 4, 2010
taylor holiday reflection #3
but i must say the stuff we have seen is old news now
we know it
its simple for us to work with
but im nervous for whats to come with the last half of the school year
Degrees to Radians is: degrees*pi/180
Radians to Degree is: radians*180/pi
Unit Circle:
90 degs. = (0,1) pi/2
180 degs. = (-1,0) pi
270 degs. = (0,-1) 3pi/2
360 degs. = (1,0) 2pi
sin=y/r
cos=x/r
tan=y/x
cot=x/y
sec=r/x
csc=r/y
SOHCAHTOA:
S = sin
O = opposite angle
H = hypotenuse
(sin = opposite/hypotenuse)
C = cos
A = adjacent angle
H = hypotenuse
(cos = adjacent/hypotenuse)
T = tan
O = opposite angle
A = adjacent angle
(tan = opposite/adjacent)
Sunday, January 3, 2010
Devin's Reflection
Sin A/a = Sin B/b = Sin C/c
-the only way to use this formula, is unless you have a pair (meaning an angle and its corresponding side)
-you plug in the factors that can be accounted for
-you use cross-multiplication to get the formula in a horizontal equation
-you use algebra to finish the equation
The Law of Cosines
opposite leg^2 = adjacent leg^2 + other leg^2 -2(adjacent leg)(other leg)cos*
-this equation is a guide to help solving this certain types of triangles
-plug in the factors that you know of into the equation
-if you have to, you are allowed to renovate the equation to be accessible to various occasions
-you use algebra to finish the equation
Area of a triangles that are not Right angles
1/2(leg)(leg)sin*
SOHCAHTOA
Sin = Opposite/Hypotenuse
Cos = Adjacent/Hypotenuse
Tan = Opposite/Adjacent
Csc = Hypotenuse/Opposite
Sec = Hypotenuse/Adjacent
Cot = Adjacent/Opposite
Stephanie's Reflection
0°
sin0=0
cos0=1
tan0=0
csc0=undefined
sec0=1
cot0=0
30°
sinπ/6=1/2
cosπ/6=√3/2
tanπ/6=√3/3
cscπ/6=2
secπ/6=2 √3/3
cotπ/6=√3
45°
sinπ/4=√2/2
cosπ/4=√2/2
tanπ/4=1
cscπ/4=√2
secπ/4=√2
cotπ/4=1
60°
sinπ/3=√3/2
cosπ/3=1/2
tanπ/3=√3
cscπ/3=2 √3/3
secπ/3=2
cotπ/3=√3/2
90°
sinπ/2=1
cosπ/2=0
tanπ/2=undefined
cscπ/2=1
secπ/2=undefined
cotπ/2=0
Reference Angles (must be between 0° and 90°)
1)find which quadrant angle is in
2)determine the sign in that quadrant (+ve or -ve)
3)subtract 180° until the angle is between 0° and 90° (0 and π/2)
1)find the reference angle using chart or calculator
2)find what quadrant you need to be in based on the sign of the value
3)use notes to move to that quadrant
To Move:
I to IV = make negative and add 360°
I to III = add 180°
I to II = make negative and add 180°
II to IV = add 180°
Unit Circle
180 pi
270 3pi/2
360 2pi
AREA OF A NON-RIGHT TRIANGLE
A=1/2(leg)(leg)sin(angle between)
RIGHT TRIANGLES
- hypotenuse opposite angle
- a=1/2bh
- SOHCAHTOA
cos theta=adjacent/hypotenuse
tan theta=opposite/adjacent
LAW OF SINES
sinA/a sinB/b sinC/c
- used when you know pairs in a non-right triangle
- you are setting up proportions
- A=1/2bh
- SOHCAHTOA
- sinΘ=opposite leg/hypotenuse
- cosΘ=adjacent leg/hypotenuse
- tanΘ=opposite leg/adjacent leg
(opposite leg)²=(adjacent leg)² + (other leg)² - 2(adjacent leg)(adjacent leg)cos°
EG: x, 5, 6 angle = 35°
x²=5²+6²-2(5)(6)cos35°
x=√(5²+6²-2(5)(6)cos35°)
x≈3.443
Area of Inscribed Shapes
A=nr²sinΘcosΘ
Terrio's New Years Blog
Degrees & Radians:
Degrees to radians= Degree times pi/180
Radians to degrees= Radians times 180/pi
So if you have 360 degrees you would multiply 360 by pi/180 and it would be 360pi/180. Then you simplifie it and you would get 2pi/1
If you have 2pi you would multipy 2pi by 180 over pi and you would get 360pi/1pi. When you simplifie this it would equal 360 degrees.
1. log5 25 = x
The 5 would be the number raised to an exponent. The x would be the exponent, and 10 would be what 5 raised to the exponent equals. So it should look like this:
5^x = 25
x would equal 2
Alicia's Reflection #20 (Christmas Holiday)
Polynomials and function notation
degree: the highest exponent
0- constant
1- linear
2-quadratic
3-cubic
4-quartic
5-quintic
** No variable can be in the denominator for a polynomial
**A root, zero, and x-intercept are the same thing
**Polynomial- equation with only addition and subtraction of terms
**Leading term- term with highest degree
**Function notation f( ) = plug in what is in ( ) for x.
**Synthetic division- used to factor.
Ex.) x^9+5x^7+4x^10+9x^2+4
A.) Is the equation a polynomial? yes
B.) What is the degree? 10
C.) What is the leading term? 4x^10
D.) What is the leading coefficient? 4
Ex.) f(x) = x^3+5x^2+5x-2
A.) find f (2)= (2)^3 +4(2)^2+1
= 8+4(4)+1
=8+16+1
= 25
Hope everyone had a good holidays....See yall tomorrow!
Saturday, January 2, 2010
Stephen's reflection
Reciprocal Relationships:
cscΘ=1/sinΘ
secΘ=1/cosΘ
cotΘ=1/tanΘ
Relationships with Negatives:
sin -Θ= -sinΘ and cos -Θ= -cosΘ
csc -Θ= -cscΘ and sec -Θ= -secΘ
tan -Θ= -tanΘ and cot -Θ= -cotΘ
Pythagorean Relationships:
sin²Θ+cos²Θ=1
1+tan²Θ=sec²Θ
1+cot²Θ=csc²Θ
Cofunction Relationships:
sinΘ=cos(90°-Θ) and cosΘ=sin(90°-Θ)
tanΘ=cot(90°-Θ) and cotΘ=tan(90°-Θ)
secΘ=csc(90°-Θ) and cscΘ=sec(90°-Θ)
When you get an equation you have to first check to see if there are any identities you can use, if not you go to algebra, after that you go back to your identities and finish the problem. This is really easy you just need to memorize the relationships.
I pretty much forgot alot of stuff like solving conics...yea....and solving problems when you have to find axis of symmetry and stuff like that with the lengthy equations so i need help with that.
Stephen's Reflection...last weeks make up
1. logbMN=logbM+logbN
2. logbM/N=logbM-logbN
3. logbM^k=KlogbM
4. log(b)B^k=k
5. b^logbK=k
If a question tells you to expand logbMN^2, then the answer is logbM+2logbN. If a problem tells you to condense log45-2log3 then you make it log45/9 which = log5. Expand means to make it bigger and condense means to make it smaller.
There are a few things i dont understand. One is remembering conics and how to solve them so if anyone can explain that for me id be thankful. Two i have trouble remembering the simple stuff in chap 1 like the quad formula and how to complete the square.
aMY'S rEflection #20 (second holiday blog)
Logarithm Properties:
logb MN = logb M + logb N
logb M/N = logb M - logb N
logb M^K = K logb M
logb b^k = k (this one i don't get..maybe i copied it wrong)
b^logb^k = k
Here are some examples:
1. log 2 + log 3 + log 4 = log 24 (mulitply: 2 x 3 x 4)
2. log 8 + log 5 - log 4 = log 10 (mulitply: 8 x 5 then divide: 40/4)
3. 2 ln 6 - ln 3 = ln 12 (raise 6 to the 2nd power = 36 the divided by 3 = 12)
4. log M - 3 log N = log M/ N^3
5. ln 2 + ln 6 - 1/2 ln 9 = ln 12/3 = ln 4
6. Expand logb MN^2....logb M + 2 logb N
7. Condense log 45 - 2 log 3....log (45/9) = log 5
8. Rewrite in exponetial form: log36 6 = 1/2....36^1/2 = 6
9. Rewrite in logarithmic form: 2^2 = 4....log2 4 = 2
Changing Bases: (Done when you can't solve a log)
Rewrite it as an exponential
Take the log of both sides
Move the variable to the front
then solve
(use the same steps when solving for x as an exponent when you can't write them as the same base)
examples:
1. log5 10 = x
5^x = 10
log 5^x = log 10
x log 5 = 1
x = 1/log 5
2. 2^x = 7
log 2^x = log 7
x log 2 = log 7
x = log 7/log 2
(we all know ms Robinson likes to use some crazy symbols ..so don't panic)
oh btw, HAPPY NEW YEARS EVERYONE!!!
Friday, January 1, 2010
Taylor holiday reflection #2
refresher anyone?
**#1
you need to see if the parabola will open up or down. think of it this was: if the first thing you see in the equation is a negative sign relate that to which way negative numbers go on a graph or think "if some thing is negative you get a thumbs down" like wise "if something is positive it gets a thumbs up" so first thing you see at the front of the equation is a negative sign? thumbs down therefore the parabola opens down. If the first thing you see is a positive number? thumbs up therefore the parabola opens up.(using analogies like this is good for memory. If you start thinking in terms of analogies you get faster at retaining information)
**#2
deciding the number of X intercepts is also an easy remembering problem to fix. first you need to answer the problembsquared - 4(a)(c)as you said you are very good at plugging in this formula because you have remembered it well.look at your answer to that and remember: positive answer is two x interceptsnegative answer is nonezero for an answer is one X interceptits better to have two than none so POSITIVE thing to have TWONEGATIVE thing to have NONE(i dont have a trick to remember zero.. i think its just a process of elimination thing.. if i didnt get a positive answer or a negative anser that means its not two x intercepts nor is it no X intercepts,, well that means its one X intercept)
**#3
to find an x intercept you solve for Xit says that in your question"find X intercept"remember "find X"(dont forget to put answer into point form. when solving for x you will always wind up having to square root. you know this meas the answer will be +/-. be sure to show this when convertine to point form. {I.E. (#,0) & (-#,0)} in many of the problems we had there was also a matter of carring a number to the other side. this is no big deal you just tack it on also. for example... if you ended with X-2= +/- square root 6/2 you would add 2 to both sides and put in point form. therefore you'd have (squareroot 6/2+2,0) & (- squareroot 6/2+2,0))
**#4
y- intercept is just taking the 0 in the y spot for the last answer and plugging it into the x spot in the equation. which then leaves you only the Y variable to solve for. Remember: "Find Y intercept""find Y"common sense will tell you the only way to do that is to plug something into the X spot.. and i told you what to plug in
**#5
Axis of semmatry is a simple conversion formula you'll have to memorize the same way you did for the quadratic formula. by writing it down everytime you solve for axis of semmatry until you see the formula in your sleep.the Formula (in case it isnt written down) is X= -b/2(a) (the a and b plug ins of course come from the original equation)your answer will be the point to put your DOTTED LINE on. because this formula solves for X you know it will pass through that point on the X line. You also know its a vertical line. so no worries.
**#6
the vertex is also just a matter of plugging in remember this step follows the step ahead of it so it retains the answer for X that means half of your vertex is solvedyou already have your X point for the vertex answer that answer is also plugged into the original equation which again leaves you to solve for y.this means you now have your vertex point because you solved for X in step 5 and your answer after plugging that in gave you the Y
FINALLY!
now that you have turned everything into points its just a matter of locating them and marking them all on your graph.After each point is marked connect the dots.just as a quick check look back and see if your parabola is supposed to open up or down if your graph matches then congratulations! everything seems to have gone well.
i know everything i've given you is alot to remember. just write down the hints and keep the sheet as a reference. it doesnt have to be word for word. just putting "step one- opens up or down? work {b-4ac} *positive thumbs up *negative thumbs down"
Taylor holiday reflection #1
i figured id share my way of remembering it
TRIGCHART
0° *sin 0= 0 *cos 0= 1 *tan 0= 0 *csc 0= undefined *sec 0= 1*cot 0= undefined
30° * sin π/6= 1/2 *cos π/6= √3/2 *tan π/6= √3/3 *csc π/6= 2 *sec π /6= 2 √3/3*cot π/6= √3
45° *sin π/4= √2/2 *cos π/4= √2/2 *tan π/4= 1 *csc π/4= √2 *sec π/4= √2 *cot π/4= 1
60° *sin π/3= √3/2 *cos π/3= 1/2 *tan π/3= √3 *csc π/3= 2 √3/3 *sec π/3= 2 *cot π/3= √3/2
90° *sin π/2= 1 * cos π/2= 0 *tan π/2= undefined *csc π/2= 1 *sec π/2= undefined *cot π/2= 0
I also discovered an easier way to memorize the chart
First you would have to set up the chart differently than it was given
It would have to look like this
Sin Cos Tan Csc Sec Cot
30
45
60
90
Just like a graph and then you fill in the parts for each
If you can memorize the sin column for the chart you can figure out the rest of the chart
Cos is just sin backwards
Tan is just sin/cos
Csc is just 1/sin
Etc. You just have to find the relations of each