Write the Word or Phrase That Best Completes Each Statement $$\cot ^ { 3 } x = \cot x \left( \csc ^ { 2 } x - 1 \right)$$

Essay

Write the word or phrase that best completes each statement or answers the question.
Establish the identity.
- $$\cot ^ { 3 } x = \cot x \left( \csc ^ { 2 } x - 1 \right)$$