Question

prove that sin(90-a)*cos(90-a)=tana/1+tan2a

Answer 1

Hi ,

LHS = sin(90 - A ) * cos ( 90 - A )

= CosA sinA ----( 1 )

RHS = tanA / ( 1 + tan² A )

= tan A / sec² A

= ( SinA/cosA ) / ( 1/ cos² A )

= ( SinA cos² A ) / cosA

= SinAcosA ----( 2 )

From ( 1 ) and ( 2 ) ,

LHS = RHS

I hope this helps you.

:)

Answer 2

Here is your answer

Hope it helps