Answer
$\cos\theta=\frac{-4}{5}$
Work Step by Step
1.We get this information from the sine value
$y=3$
$r=5$
2. We can use y and r to find x (we need to remember that sign of x depends on quadrant, since it ends in quadrant II, x must be negative)
$r=\sqrt {x^{2}+y^{2}}$
$x=-\sqrt {r^{2}-y^{2}}=-\sqrt {5^{2}-3^{2}}=-\sqrt {25-9}=-\sqrt {16}=-4$
3.Then insert values,
$\cos\theta=\frac{-4}{5}$
