Exercise 5 Page 523

Before we rewrite the given expression, let's start by recalling the values of the three main trigonometric functions for the most important angles.

	$\sin \theta$	$\cos \theta$	$\tan \theta$
$\theta =0$	$0$	$1$	$0$
$\theta =\frac{\pi }{6}$	$\frac{1}{2}$	$\frac{\sqrt{3}}{2}$	$\frac{\sqrt{3}}{3}$
$\theta =\frac{\pi }{4}$	$\frac{\sqrt{2}}{2}$	$\frac{\sqrt{2}}{2}$	$1$
$\theta =\frac{\pi }{3}$	$\frac{\sqrt{3}}{2}$	$\frac{1}{2}$	$\sqrt{3}$
$\theta =\frac{\pi }{2}$	$1$	$0$	-
$\theta =\pi$	$0$	$\text{-}1$	$0$
$\theta =2\pi$	$0$	$1$	$0$

Let's now recall the Angle Difference Formula for a sine. We will use this identity to rewrite the given expression.