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If cot⁴θ + cot²θ = 2.2, then csc⁴θ − csc²θ = ?
A0
B1.1
C2.2
D3.3
Answer & Solution
Correct answer: C. 2.2
1. Use csc²θ = 1 + cot²θ.
2. csc⁴θ − csc²θ = csc²θ(csc²θ − 1) = (1 + cot²θ)(cot²θ).
3. Expanding: cot²θ + cot⁴θ = cot⁴θ + cot²θ = 2.2.
_Source: RRB Group D CEN-02/2018 PYQ, Q.10._