Answer
See below.
Work Step by Step
$LHS=\frac{sec\theta}{1-sin\theta}\times\frac{1+sin\theta}{1+sin\theta}=\frac{sec\theta(1+sin\theta)}{1-sin^2\theta}=\frac{(1/cos\theta)(1+sin\theta)}{cos^2\theta}=\frac{1+sin\theta}{cos^3\theta}=RHS$
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