Question

what is the value of (cos^67- sin^23)

Answer 1

=cos 67 - sin 23
=cos 67 - cos ( 90 - 23)
=cos 67 - cos 67
=0

Here is your answer

Answer 2

$cos( 90 - theta) = sintheta$

$cos^{2} 67 - sin {}^{2} 23$

$cos {}^{2} (90 - 23) - sin {}^{2} 23$

$sin {23 - sin } {}^{2} 23$

$= 0$

HOPE IT HELPS YOU!!!