Answer
See below.
Work Step by Step
Using trigonometric identities, we have:
$LHS=\frac{sin\theta/cos\theta-cos\theta/sin\theta}{sin\theta/cos\theta+cos\theta/sin\theta}=\frac{sin^2\theta-cos^2\theta}{sin^2\theta+cos^2\theta}=1-2cos^2\theta=RHS$
