Question

Resolva:
a) cosx (vezes) cosx
b) cosx (vezes) x

Answer 1

a)
cos x . cos x = 1/2.[cos (x + x) + cos (x - x)] = 1/2.[cos 2.x + cos 0] = 1/2.[cos (2.x) + 1] = (cos (2.x) + 1) / 2

b) cos x.x = cos x²