# How do you evaluate sin^-1(sin (5pi/6))?

${150}^{o}$
${\sin}^{-} 1$ and $\sin$ cancel each other out. They are opposite functions - its like multiplying and dividing by the same number.
This just leaves $\frac{5 \pi}{6}$, where $\pi$ radians is equal to ${180}^{o}$, in which case
$\frac{5 \pi}{6} = \frac{5 \cdot {180}^{o}}{6} = {900}^{o} / 6 = {150}^{o}$