



 
Hi Holly, Using the chain rule you can show that the derivative of $f(x) = 2 \sin^3 x  3 \sin x$ is \[f'(x) = 6\; \sin^2 x \cos x  3 \cos x\] First pull out the common factor of $3 \cos x$ and then use the double angle expression for the cosine function to simplify the expression. Harley  


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