Question

prove that cos 105 + cos 15=sin 75-sin 15

Answer 1

LHS =)we have;

cos105 + cos15 


=)cos (90+15) + cos (90-75)


=)-sin15+sin75

=)-sin(15-sin75)


=)sin75-sin15

Hence, LHS=RHS

Answer 2

Answer:

Step-by-step explanation:

LHS =cos105 + cos15

=cos (90+15) + cos (90-75)

=-sin15+sin75

=sin75-sin15=RHS