#### 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.

Published by
Pearson

ISBN 10:
0321671775

ISBN 13:
978-0-32167-177-6

False

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