# Thread: Unit circle - Convert cos to sin

1. ## Unit circle - Convert cos to sin

What is $cos 480$ in terms of $sin$?

2. Originally Posted by nerdzor
What is $cos 480$ in terms of $sin$?
$\cos (480 ^\circ) = -\frac{1}{2}$
$\sin ^{-1} (-\frac{1}{2}) = -30^\circ = 210^\circ =330^\circ= 570^\circ$

But for unit circle, we select $-30^\circ$ as we are measure as close to zero as possible. In other words, the range of $\sin ^{-1}$ is restricted to [–90°, 90°].