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What is the answer to this trig substitution problem (x^4)?
Wow, that's a lot of steps. How do we simplify further?
We can expand the squared term and use the identity sin^2(theta) = (1 - cos(2theta))/2 to get: 8integral of (cos^4(2theta) - 2cos^3(2theta) + 3cos^2(2theta) - 2cos(2theta) + 1) d(theta).