Trigonometry (10th Edition)

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

Chapter 2 - Acute Angles and Right Triangles - Section 2.3 Finding Trigonometric Function Values Using a Calculator - 2.3 Exercises - Page 64: 51

Answer

False

Work Step by Step

$\cos 40^{\circ} = 0.7660444431$ $1 - 2\sin^{2} 80^{\circ} = 1-1.939692621 = -0.939692621$ They are not equal, therefore false.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

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.