Trigonometry (10th Edition)

Published by Pearson
ISBN 10: 0321671775
ISBN 13: 978-0-32167-177-6

Chapter 1 - Trigonometric Functions - Section 1.1 Angles - 1.1 Exercises - Page 9: 115

Answer

90$^{\circ}$ is between 1st and 2nd quadrant.

Work Step by Step

1. This is "if applicable" situation your book is talking about 2. 90$^{\circ}$+360$^{\circ}$=450$^{\circ}$ 90$^{\circ}$-360$^{\circ}$=-270$^{\circ}$ Co-terminal angles always in the same quadrant as original angle.
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