Question

I need some help with questions 5-10

http://locker.palcs.org/~jbaskwill/pc/5-3practice.PDF

Answer 1

It has to do with Sum and Difference Identities in Pre-Calc

Answer 2

no 5 -> we know that cosx cosy+sinx siny = cos(x-y)
therefore cos133 cos58+ sin133 sin58 = cos(133-58) = cos75
the answer is B

Answer 3

6) sinx cosy +cosx siny = sin(x+y)
sin(π/5) cos(π/11) +sin(π/11) cos(π/5) = sin(π/5 + π/11)
= sin(16π/55)
answer : D

Answer 4

7) (tanx - tany)/(1+tanx tany) = tan(x-y)
so the answer is tan 48

Answer 5

thank you soo much. you helped a lot!

Answer 6

you're welcome, sorry i can't help for number 8-10

Answer 7

its ok

Answer 8

i can help with 9 and 10, you need to use the sum and difference formulas
9) Notice its a sin function because it crosses the x-axis around x=2 meaning the sin function has been shifted to the right 2 units.
Now use y = sin(x+(-2)) = sin(x)cos(-2) +cos(x)sin(-2)

10) This one is a cosine function because at x=3 it starts a new period at 1 so the cosine function has been shifted right 3 units.
So y = cos(x+(-3)) = cos(x)cos(-3) - sin(x)sin(-3)

Answer 9

thank you