1. ## trig.

Prove that the equation is an identity

cosθ(secθ-cosθ)=sin^2 θ

Prove that the equation is an identity

cosθ(secθ-cosθ)=sin^2 θ
Two things you need to know here:

• $\sec\theta = \frac{1}{\cos\theta}$

• $\sin^2\theta = 1-\cos^2\theta$

3. cosθ(secθ-cosθ)=sin^2 θ, the left hand side of the equation seems tempting,

cos θ (1/cos θ - cos θ) =

cos θ (1/cos θ) - cos θ cos θ =

1 - cos^2 θ = ?