Are you sure? It's important to Remember these identities: sin2x=2−1(cos2x−1), cos2x=21(cos2x+1), cos4x=2cos2x−1
Yeah definitely remember those identities, or at least remember how to derive them from sin2x+cos2x=1 and cos2x=cos2x−sin2x I'd recommend writing them down at the side of any working out so that you are sure of the trig identities that you use, and to possibly remind yourself that you can use them if you get stuck in a question
For C3 and C4, Here's a good way of remembering differential and integral of sinx, cosx, -sinx and -cosx (these will not be given in the formula booklet):