# What is the derivative of sin^2 (6x)?

I would use the Chain Rule deriving ${\left(\right)}^{2}$ first then the $\sin$ and finally the argument $6 x$:
$2 \cdot \sin \left(6 x\right) \cdot \cos \left(6 x\right) \cdot 6 = 12 \sin \left(6 x\right) \cos \left(6 x\right)$