1. ## compound angle formulas

i'm not sure how to do this kind of question:

" angles x and y are located in the first quadrant such that sinx= 3/5 and cos y=5/13.

a) determine an exact value for cosx
b) determine an exact value for siny "

2. Originally Posted by ineedhelp1234
i'm not sure how to do this kind of question:

" angles x and y are located in the first quadrant such that sinx= 3/5 and cos y=5/13.

a) determine an exact value for cosx
b) determine an exact value for siny "
a) $\sin X=\frac{y}{r}=\frac{3}{5}$

Use $r^2=x^2+y^2$ to solve for x.

$\cos X=\frac{x}{r}$

b) $\cos Y=\frac{x}{r}=\frac{5}{13}$

Use $r^2=x^2+y^2$ to solve for y.

$\sin Y=\frac{y}{r}$