Prove Trig Identity: CosθSinθ = Cos2θ+CosθSinθ

[Bradyns]

Prove:
$\frac{CosθSinθ}{1 + Tanθ}$ = Cos²θ
===========================
I multiply out the denominator to get:

CosθSinθ = Cos²θ + CosθSinθ

I cannot seem to prove it.

Starting to think it's a trick question.. :/

 

[krome]

It most certainly is a trick question because the supposed identity doesn't even work if you plug in theta = 0. The left side is 0 while the right is 1, in this case!

 

[Millennial]

You might be asked to solve the equation instead of proving the identity, and the solutions of the equation are the zeros of cosine, id est odd integer multiples of $\pi/2$.