heyy, so this week was pretty much a review for our chapter 9 test on tuesday. We had a take home quiz for chapter 9 that was pretty easy once we learned the law of cosines. I do really good with those kind of questions but the minute i see a word problem its like i completely forget how to solve them. i need to figure out a way to know what method to use based upon the information that the word problem gives. if anyone has any tricks to know how to solve the word problems, it would help me out alot for the test on tuesday. Also, if anyone can help me with # 8 and #10 on the chapter test it would help me out greatly.
Review of chapter 9 Right triangles:
*the hypotenuse is opposite the right angle.
*A= 1/2 bh
*SOHCAHTOA---stands for....
Sin θ= opposite leg/hypotenuse
Cos θ= adjacent leg/hypotenuse
Tan θ= opposite leg/adjacent leg
*To find the area of a non right triangle use this formula:
*A= 1/2 (leg)(leg)SIN(angle b/w)
*When you have a non right triangle that has pairs, use the law of sines:
Sin A/a = Sin B/b= Sin C/c
*All you are doing is setting up a proportion.
**Remember to solve for an angle, you have to take the inverse.
*To solve a triangle with no angles, use the Law of Cosines:
(opp leg)^2= (adj leg)^2 + (other adj leg)^2 -2(adj leg)(adj leg) Cos(angle b/w)
*use an angle to orient yourself like SOHCAHTOA!!
Goodluck to everyone on the test!!
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well we don't have to do #10..
ReplyDelete#8:
you use the law of cosines
x^2 = 3.5^2 + 3.5^2 - 2 (3.5)(3.5) cos 67
take the square root and you get
x = 3.86m
ok for the word problem stuff....if it gives a prolem that gives an object or person that is a certain distance away from something or if there is angle of elevation, that is a right triangle and you would use SOHCAHTOA. If it doesnt say any of that stuff then what i usually do is draw a regualar triangle and plug in stuff that is given and if there are pairs, then law of sines is used and if there are 2 legs with an angle inbetween then law of cosines is used.
ReplyDeleteAlright well im going to comment on myself. My question is how do you move from certain quadrants when finding angles for sin, -sin, cos, -cos, tan, and -tan. Just remember these rules:
ReplyDeleteI - IV : make negative then add 360
I - III : add 180
I - II : make negative then add 180
I - IV : add 180
Also where is sin positve and negative, where is cos positive and negative, and also tan.
Sin- positive in 1 and 2. negative in 3 and 4
Cos- positive in 1 and 4. negative in 2 and 3
Tan- positive in 1 and 3. negative in 2 and 4