Question

How do you integrate `int cos((2x)/3)` from [0, pi/2]?

Answer 1

`int_0^(pi/2) cos((2x)/3)dx = 3/2 int_0^(pi/2) cos((2x)/3)d((2x)/3) = 3/2 [sin((2x)/3)]_0^(pi/2) = 3/2( sin (pi/3) -sin 0) = (3sqrt(3))/4`