Question

How do you find the integral of `int cos^2theta`?

Answer 1

Use the double angle formula for cosine to reduce the exponent.

Explanation:

`cos(2theta) = 2cos^2theta -1`

So `cos^2theta = 1/2(1+cos(2theta))`

Hence the integral is

#int cos^2theta d(theta)=int 1/2*(1+cos2theta) (d theta)= theta/2+1/4*sin2theta+c#