Question

what is the value of
$( \cos^{2} 67 ^{o} \: - \sin^{2} 23 ^{o} )$
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Answer 1

$Question: \cos {}^{2} 67 - { \sin }^{2} 23 \\ \\ \\ Now, \\ \cos(67) = \cos(90 - 23) = \sin(23) \\ \\ \cos {}^{2} 67 = \sin {}^{2} 23 \\ \\ therefore, \\ \\ \cos {}^{2} 67 - { \sin }^{2} 23 = 0$

Answer 2

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