Chapter 2 - Acute Angles and Right Triangles - Section 2.1 Trigonometric Functions of Acute Angles - 2.1 Exercises - Page 51: 9

$\csc \theta = \frac{1}{\sin\theta}$ $\csc 60^{\circ}= \frac{1}{\sin 60^{\circ}} = \frac{1}{\frac{\sqrt 3}{2}}= \frac{2}{\sqrt 3}$

$\csc \theta = \frac{1}{\sin\theta}$ (Inverse property) $\csc 60^{\circ}= \frac{1}{\sin 60^{\circ}} = \frac{1}{\frac{\sqrt 3}{2}}= \frac{2}{\sqrt 3}$ (Special angle)