Question #8f299

1 Answer
vince
Oct 19, 2017

#sin(theta)/4 + theta/2 + cte#

Explanation:

Use the duplication formula :
#cos(2 theta) = 2 cos^2(theta) -1#
therefore
#cos^2(theta) = (cos(2theta) + 1)/2#
(we have "linearised" #cos^2(theta)#)

Now, you can easily integrate :
#int cos^2(theta) d theta = 1/2 int (\cos(2 theta) + 1)d theta = 1/2 [sin(2theta)/2 + theta] + cte#

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