Question

Prove that sin (90-theta) cos (90-theta)= tanA /tanA+1

Answer 1

Please see attached picture for full solution.

I changed the rhs to tanθ/tanθ+1 since the angle cannot be A and θ.

tanθ= sinθ/cosθ

cosθ/sinθ= cotθ= 1/tanθ

From 4th last line, here is the step I skipped:

1 ÷ [1 +(1/tanθ)] = 1 ÷ [(tanθ/tanθ)+(1/tanθ)]