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

y = 9sin(x)cos(x)

Find all points where tangent line is horizontal.

3. The attempt at a solution

I get y' = 9cos^2x - 9sin^2X

I plug in zero for the slope and get 9 but I'm stumped after that. How can I get all the horizontal tangent line points?

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# Homework Help: More tangent lines

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