Chapter 1 - Trigonometric Functions - Section 1.4 Using the Definitions of the Trigonometric Functions - 1.4 Exercises - Page 37: 82

$\cot\theta=\frac{\cos\theta}{\sin\theta}$

1. Start by taking the reciprocal of both sides of the tangent equation $(\frac{\sin\theta}{\cos\theta})^{-1}=(\tan\theta)^{-1}$ $\frac{\cos\theta}{\sin\theta}=\frac{1}{\tan\theta}$ 2. One over tangent is a cotangent. That it is $\cot\theta=\frac{\cos\theta}{\sin\theta}$