Prove the Identity $$\tan ^ { 5 } x = \tan x \left( \sec ^ { 4 } x - 2 \sec ^ { 2 } x + 1 \right)$$

Essay

Prove the identity.
- $$\tan ^ { 5 } x = \tan x \left( \sec ^ { 4 } x - 2 \sec ^ { 2 } x + 1 \right)$$