Question

Can someone explain how ∫cos2xdx = (1/2)sin2x

Answer 1

try using u-substitution, with u = 2x.
the only other thing to know is that the integral of cosine is sine. (because the derivative of sine is cosine)

Answer 2

and you can also confirm that it is true because the derivative of sin(2x)/2 = cos(2x)/2 * 2 = cos(2x)

Answer 3

ohhhh I see it now thanks

Answer 4

No problem. :)