Chapter 1, Problem 13P

Two trigonometric identities are given by:

$(a)\tan 3x=\frac{3\tan x-{\tan }^{3}x}{1-3{\tan }^{2}x}(b)\cos 4x=8\left({\cos }^{4}x-{\cos }^{2}x\right)+1$

For each part, verify that the identity is correct by calculating the values of the left and right sides of the equation, substituting x = 24°.