I have to find all answers to these on the interval 0-2 pi, I think I'm getting them right but I'm not 100% positive

For the first one I had

and I did

and on the interval 0-2pi I got

the second one I have to do

and I got

and for the interval I got

are there any answers on the interval that I am missing?

also if anyone can help me with this identity

(cscx-cotx)^2=(1-cosx)/(1+cosx)

I've tried everything but have gotten nowhere