Find dy/dx in the following?
1) y=sin^-1(1-x^2/1+x^2),0<x<1
2) y=sec^-1(1/2x^2-1),0<x<1/root2
3) y=tan^-1(3x-x^3/1-3x^2),-1/root3<x<1/root3
4)sin^2y+cosxy=pie
Please solve step by step with full explaination.