Prove that: `(cos2theta)/(1+sin2theta)=tan(pi/4-theta)`

Explanation

To prove that \(\frac{\cos 2\theta}{1 + \sin 2\theta} = \tan\left(\frac{\pi}{4} - \theta\right)\), we will start by using trigonometric identities.

### Step 1: Rewrite \(\cos 2\theta\) and \(\sin 2\theta\)
Using the double angle formulas:
\[ \cos 2\theta = \cos^2 \theta - \sin^2 \theta \]
\[
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