This week wasn't that difficult and we even had a lucky break by having the test pushed back until monday. The week consisted of learning the section of chapter eight that focuses on using the Trig identites
TRIG IDENTITIES
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 Relationsihps
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)
This section isnt a difficult section to comprehend it just takes alot of memorization.
What i dont feel like i understand is the section involving quadrent shifts to find the answer
if anyone could give me basic easy peasy to remember and follow steps that would be great
Thanks!
do you mean moving one quadrent to another? if you are here you go...
ReplyDeleteI to II : make negative then add 180 (or just subract from 180)
I to III : add 180
I to IV : make negative then add 360 (or justjust subract from 360)
Sin- positive in I and II & negative in III and IV
Cos- positive in I and IV & negative in II and III
Tan- positive in I and III & negative in II and IV
hope this helped...
If you are talking about once you've isolated the trig function and have like cos(x)=-1/2
ReplyDeletePretty much you take the cos inverse of -1/2. It will be negative already, so you add 180 and 360 because you are finding where cos is negative. Does that make sense?
If there is a square root involved, you find all four quadrants.
Quadrant shifting is pretty easy. Remember that you want to keep your answers under 360 at all times so lets say if your answer for the first quadrant is 56. The first quadrant goes to 90 degrees, the second goes to 180, the third goes to 270 and the fourth goes to 360. So if you want to get to quadrant 2, just subtract 56 from 180. If you want to get in quadrant 3, you want to be between 180 and 270 so just add 56 to 180. And to get to the fourth quadrant then you just keep the number under 360 by subtracting 56 from 360.
ReplyDelete