## Trigonometry (10th Edition)

Published by Pearson

# Chapter 1 - Trigonometric Functions - Section 1.4 Using the Definitions of the Trigonometric Functions - 1.4 Exercises: 83

False

#### Work Step by Step

1. Lets start by substituting values into expression: $\cos90^{\circ}+\sin90^{\circ}=0+1=1$ (correct) $\cos270^{\circ}+\sin270^{\circ}=0+(-1)=-1$(false) $\cos60^{\circ}+\sin60^{\circ}\ne1$ another counter example

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