Originally Posted by

**realintegerz** How do I do these problems?

1) cos ^ -1 ( cos (7 pi/4) )

2) sin ^ -1 ( - sq. root 3 /2 )

The answer to the first problem is supposed to be pi/4 and 7 pi/4

but I don't get how to do these? I know our answers are to be in terms of the unit circle, so if you can explain it in detail please do so, and were not allowed to use a calculator to solve these

I have no clue on how to do these inverse trig functions, I asked on yahoo answers and people weren't explaining well enough