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

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Answer 1 · 2015-09-26T03:36:11

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

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

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

Hence the integral is

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

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