Answer
See below.
Work Step by Step
1. $LHS=csc^4\theta-csc^2\theta=csc^2\theta(csc^2\theta-1)=csc^2\theta(cot^2\theta)$
2. $RHS=cot^4\theta+cot^2\theta=cot^2\theta(cot^2\theta+1)=cot^2\theta(csc^2\theta)=LHS$
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