Question

I need help
cos(x-y) if cos x =15/17 and sin y = 5/13

Answer 1

Subtraction formulas for cos
\[\Large \cos(x-y)=(\cos x \cos y)+(\sin x \sin y)\]

Answer 2

Ok thank you
So I just plug in my information?

Answer 3

You have two triangles in this situation, one with x and one with y

Answer 4

Once you find those, then you can find what cosy and sinx are, repsectively.
@DanJS we need to find those first however^^ (cosy & sinx)

Answer 5

So to draw triangles?

Answer 6

^ I have to draw triangles

Answer 7

I've already drawn them, but yes, since they only give us cosx and siny we need

cosx
cosy
sinx
siny

to use our formula we only know half of them we have to find the other two, but the first step is to find out what z_1 and z_2 are in my drawing

Answer 8

Do you know how to solve for them?

Answer 9

Yea

Answer 10

Ok, solve for them and tell me what you get and I'll verify with you

Answer 11

I kinda forgot but I got
Z_1 = 8
Z_2 = 12

Answer 12

@doulikepiecauseidont

Answer 13

I'm sorry, I had to step away and yes those are the value so now we have