## anonymous 4 years ago Tips and answer to finding principal value

1. anonymous

X =$\sin^{-1} (\sqrt{2}/2)$

2. anonymous

look at a cheat sheet if you do not remember which angle (number) has sine of $\frac{\sqrt{2}}{2}$ you will see that it is $\frac{\pi}{4}$ and although there are infinitely many others, this is the only one in the interval $[-\frac{\pi}{2},\frac{\pi}{2}]$