SSC GD Constable 2012 · Question 63 of 95

1 The value of cosec2 18∘ − cot2 72 ∘ is 1

A3 2
B3 1
C2
D1Correct

Answer: D. 1

Explanation

1 cosec2 18∘ − cot2 72 ∘ 1 = cosec 2 18∘ − tan2 72∘ (∵ cot2 ⊖ = tan2 ⊖) = cosec 2 18∘ - tan2 (90 − 72)∘ = cosec 2 18∘ - sec2 18∘ (∵ sec2 ⊖ = tan2 (90∘ − ⊖)) cosec2 18∘ - sec2 18∘ =1(∵ cosec2 ⊖ - sec2 ⊖=1)

Source: Solved SSC GD 2012 Shift 1 Paper with Solutions — Testbook · reliable-secondary

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