Some trigonometric functions questions

Help needed on these also. Either solved or information to help me solve them myself would be vcery helpful. thanks a million.......

1)Prove that:

A) cosx/1-sinx - cosx/1+sinx = 2tanx

B) sinx/sinx+cosx + cosx/sinx-cosx = 1/2sin^2x-1

2) a) State the amplitude (A) the period(T) and the frequency(F) for

the periodic function 120 sin(100pi t)V.

b) Through how many degrees does a wheel rotate in 10ms if its

angular velocity is 8 rad/s.

c) Sketch one cycle of the given function showing the values of

each variable where the curve crosses the axis.

V=50sin(4.2*10^2t)