Question

If 2cos2 Ɵ – 5cos Ɵ + 2 = 0,00 < Ɵ < 900 , then the value of (cosec Ɵ + cot Ɵ) is :

A √3 Correct Answer Incorrect Answer
B 1/3 Correct Answer Incorrect Answer
C 1/√3 Correct Answer Incorrect Answer
D 2√3 Correct Answer Incorrect Answer

Solution

2cos²θ-5cosθ+2 = 0, 0°<θ<90° 2cos²θ-4cosθ-cosθ+2=0 (2cosθ-1) (cosθ-2) = 0 ∴ cosθ = ½ θ = 60° ∴ cosecθ + cotθ = cosec60° + cot60° = 2/ √3 + 1/ √3 = √3

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