A few questions I could use some help on:

1) express the function in terms of sine only.

g(x + h) - g(x)/h = -cosx (1-cosh/h) - sinx (sinh/h)

2) write the expression in terms of sine only

3 sin pi x + 3 (square root 3) cos pi x

3) prove the cofunction

csc(pi/2 - u) = sec u

Thanks in advance.