Question: What values of the constant m if any is

\[f\left( x \right)=\left\{ \begin{aligned} & \sin 2x\,\,\,\,\,\,x\le 0 \\ & mx\,\,\,\,\,\,\,\,\,\,\,\,\,x>0 \\ \end{aligned} \right.\]

a.) continuous at x = 0

b.) differentiable at x = 0.