# Chapter 4 - Section 4.2 - Trigonometric Functions: The Unit Circle - Exercise Set - Page 549: 76

$a + b - c$

#### Work Step by Step

Note that the angles $t+2\pi$ and $t + 4\pi$ are both coterminal with the angle $t$ since $2\pi$ and $4\pi$ are multiples of $2\pi$. Note further that coterminal angles have the same value for the trignomoetric functions. Thus, the given expression is equivalent to $=\sin{t} + \cos{t} - \tan{(t+\pi)}$ Recall that the period of the tangent function is $\pi$. This means that the angles $t$ and $t+\pi$ have the same value as they are one period apart. Thus, the expression above is equivalent to: $=\sin{t} + \cos{t} - \tan{t}$ Use the given to obtain: $=a + b - c$

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.