Chapter 11, Problem 6P

Use the commands from Section 11.2 to show that:

(a) $\tan (3x)=\frac{3\tan x-{\tan }^{3}x}{1-3{\tan }^{2}x}$

(b) $\sin (x+y+z)=\sin x\cos z+\cos x\sin y\cos z+\cos x\cos y\sin z-\sin x\sin y\sin z$