Can somebody help me with these?

1. Simplify the expression sinx (cscx - sin x)

2. rewrite the expression cos^2 / (1 + sin x) so that there is no fraction

3. use the half-angle formula to simplify the expression sqrt ((1+cos(4x))/2)

4. Use the following to find the exact value of sin(x/2). cosx = -4/5, x is in quadrant III

5. Evaluate the expression sin^2(355pi/ 113) + cos^2 (355pi/113)

6. verify the identity cos x/(1 + sinx) + cosx/(1-sinx) = 2 secx

Thank you!

Isabel