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) $\displaystyle \sin X=\frac{y}{r}=\frac{3}{5}$
Use $\displaystyle r^2=x^2+y^2$ to solve for x.
$\displaystyle \cos X=\frac{x}{r}$
b) $\displaystyle \cos Y=\frac{x}{r}=\frac{5}{13}$
Use $\displaystyle r^2=x^2+y^2$ to solve for y.
$\displaystyle \sin Y=\frac{y}{r}$