Prove the following identities: `(sec-tantheta)/(sectheta+tantheta)=1-2secthetatantheta+2tan^2theta`

Explanation

To prove the identity

\[ \frac{\sec \theta - \tan \theta}{\sec \theta + \tan \theta} = 1 - 2 \sec \theta \tan \theta + 2 \tan^2 \theta, \]

we will start with the left-hand side (LHS) and manipulate it to show that it equals the right-hand side (RHS).

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