Question

sinø sin (90-ø)- cosø cos(90-ø)

Answer 1

=sin @ cos @ - cos @ sin @
=0

Answer 2

hey, mate here is ur Ans
we know that
$\sin(90 - \alpha ) = \cos( \alpha ) \\ and \: \cos(90 - \alpha ) = \sin( \alpha ) \\ so \: \sin( \alpha ) \cos( \alpha ) - \cos( \alpha ) \sin( \alpha ) \\ = 0$