## Algebra 2 (1st Edition)

$a=r \cos \theta$ and $b=r \sin \theta$
The Trigonometric Identities are written as below: a) $\sin \theta=\dfrac{Opposite}{Hypotenuse}$ $\sin \theta=\dfrac{b}{r}$ This gives: $b=r \sin \theta$ b) $\cos \theta=\dfrac{Adjacent}{Hypotenuse}$ $\cos \theta=\dfrac{a}{r}$ This gives: $a=r \cos \theta$