(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

How do you integrate a product of two trigonometric functions of x, when the argument is different, ie:

what is the integral of

sin x cos 3x

I ought to know this, but don't seem to be able to do it.

Thanks in adv!

2. Relevant equations

3. The attempt at a solution

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# Integrating product of trig functs with different args

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