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So, I have a general question first. What happens to the periodicity when we multiply two periodic trig functions with one another ?

The next one is very specific, what is the period of the function $g(x)=\sin{(ax)}\cos{(bx)}$, where $a$ and $b$ are rational numbers ? I'd be interested in a proof of sorts.

Cheers, Dave

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    You might find it helpful to think about the lowest common multiple of the periods.2012-04-02

3 Answers 3