Question

Cos a sin (90°-a)+sin a cos (90°-a)

Answer 1

Answer:

1

Step-by-step explanation:

cos(a)sin(90°-a)+sin(a)cos(90°-a)

= cos(a)cos(a)+sin(a)sin(a)   (cos(90°-a)= sin(a) ; sin(90°-a) = cos(a))

=cos²a+sin²a

= 1