To prove the identity \(\csc 2\theta + \cot 2\theta \equiv \cot \theta\), we start by expressing \(\csc\) and \(\cot\) in terms of sine and cosine.
We know:
\(\csc 2\theta = \frac{1}{\sin 2\theta}, \quad \cot 2\theta = \frac{\cos 2\theta}{\sin 2\theta}\)
Using the double angle formulas:
\(\sin 2\theta = 2 \sin \theta \cos \theta, \quad \cos 2\theta = \cos^2 \theta - \sin^2 \theta\)
Substitute these into the identity:
\(\csc 2\theta + \cot 2\theta = \frac{1}{2 \sin \theta \cos \theta} + \frac{\cos^2 \theta - \sin^2 \theta}{2 \sin \theta \cos \theta}\)
Combine the fractions:
\(= \frac{1 + \cos^2 \theta - \sin^2 \theta}{2 \sin \theta \cos \theta}\)
Since \(\cos^2 \theta - \sin^2 \theta = \cos 2\theta\), we have:
\(= \frac{1 + \cos 2\theta}{2 \sin \theta \cos \theta}\)
Using the identity \(1 + \cos 2\theta = 2 \cos^2 \theta\), we get:
\(= \frac{2 \cos^2 \theta}{2 \sin \theta \cos \theta} = \frac{\cos \theta}{\sin \theta} = \cot \theta\)
Thus, the identity is proven.