I would use the following:
So I was trying to solve this problem arcsin(sin(-3pi/5)
and so far I got that the arcsin(sin) can't cancel because the -3pi/5 is out the range of pi/2<x<-pi/2
So I looked for the reference angle...
and I know that -3pi/5 will lay on QIII because is going clockwise.
So I looked at the theta hat, and I see that theta hat is -2pi/5..
Is this right... or do I have a mistake... please help. I kind it feel that I did something wrong.