If 3sin2θ - cosθ - 1 = 0, 0º < θ < 90º, then what is the value of cot θ + cosecθ?
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Correct answer: C
Explanation
The correct answer is option 3 i.e. √5.
⇒ 3sin2θ - cosθ - 1 = 0
⇒ 3(1 - cos2θ) - cosθ - 1 = 0
⇒ 3 - 3cos2θ - cosθ - 1 = 0
⇒ 3cos2θ + cosθ - 2 = 0
⇒ 3cos2θ + 3cosθ - 2cosθ - 2 = 0
⇒ 3cosθ(cosθ + 1) - 2(cosθ + 1) = 0
⇒ (cosθ + 1)(3cosθ - 2) = 0
⇒ Cosθ = 2/3 , -1
Cosθ = 2/3 = B/H
By using Pythagoras theorem,
P2 = 32 - 22
P = .
⇒ cot θ + cosecθ = 2/ + 3/ = .