# Math Help - Differentiating Cos^3

1. ## Differentiating Cos^3

Hi Guys

This is a length of curve question, but I dont know how to differentiate $2 cos^3 x$ or $2sin^3 x$

2. Originally Posted by khanim
Hi Guys

This is a length of curve question, but I dont know how to differentiate $2 cos^3 x$ or $2sin^3 x$

hint : $\frac{d}{dx}( \cos^3 x)= \frac{d( \cos^3 x) } {d (\cos x)} \cdot \frac{d( \cos x)}{dx}=3 ( \cos^2 x) (- \sin x)$