Trigonometry (11th Edition) Clone

Published by Pearson
ISBN 10: 978-0-13-421743-7
ISBN 13: 978-0-13421-743-7

Chapter 2 - Acute Angles and Right Triangles - Section 2.3 Finding Trigonometric Function Values Using a Calculator - 2.3 Exercises - Page 67: 55

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.
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