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  1. If 1 + cos²θ = 3 sinθ cosθ, then the integral value of
    cot θ0 < θ < πis
    2
    1. 1
    2. 2
    3. 0
    4. 3
Correct Option: A

1 + cos²θ = 3 sinθ . cosθ
Dividing both sides by sin²θ

1
+
cos²θ
=
3sinθcosθ
sin²θsin²θsin²θ

⇒ cosec²θ + cot²θ = 3 cot θ
⇒ 1 + cot²θ + cot²θ = 3 cotθ
⇒ 2 cot²θ – 3 cotθ + 1 = 0
⇒ 2 cot²θ – 2 cotθ – cotθ + 1 = 0
⇒ 2 cot²θ (cot θ – 1) – 1 (cot θ – 1) = 0
⇒ (2cot θ –1) (cot θ –1) = 0
⇒ cot θ =
1
or 1
2



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