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## Homework Statement

sin-1 (-1/2) = -pi/6

## The Attempt at a Solution

I was wondering why.

Compare to cos-1(-sqrt(2)/2) = 3pi/4, this is done by pi/4 + pi/2

since cos is negative in Q2 AND Q3, this statement is valid, and the arcos is within -pi/2 and pi/2, so my answer is valid. well, i guess?

now, back to the problem with sin-1(-1/2)

how is it -pi/6? i know Q2 and Q2 are negative sin....

thanks.