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If  sin⁡2θ−3sin⁡θ+2cos⁡2θ=1\frac{\sin^2θ - 3\sinθ + 2}{\cos^2θ} = 1cos2θsin2θ−3sinθ+2​=1, then what is the value of θ?
Question

If  sin2θ3sinθ+2cos2θ=1\frac{\sin^2θ - 3\sinθ + 2}{\cos^2θ} = 1, then what is the value of θ?

A.

45°

B.

60°

C.

30°

D.


Correct option is C

Given:
sin2θ3sinθ+2cos2θ=1\frac{\sin^2θ - 3\sinθ + 2}{\cos^2θ} = 1​​
Formula Used:
cos2θ=1sin2θ\cos^2θ = 1 - \sin^2θ​​
Solution:
sin2θ3sinθ+2=cos2θ\sin^2θ - 3\sinθ + 2 = \cos^2θ​​
sin2θ3sinθ+2=1sin2θ\sin^2θ - 3sinθ + 2 = 1 - \sin^2θ​​
2sin2θ3sinθ+1=02\sin^2θ - 3\sinθ + 1 = 0​​
2sin2θ2sinθsinθ+1=02\sin^2θ - 2\sinθ - \sinθ + 1 = 0​​
2sinθ(sinθ1)1(sinθ1)=02\sinθ(\sinθ - 1) - 1(\sinθ - 1) = 0​​
(2sinθ1)(sinθ1)=0(2\sinθ - 1)(\sinθ - 1) = 0​​
sinθ=12\sinθ = \frac{1}{2}​ or sinθ=1 \sinθ = 1​​
If sinθ=1,cosθ=0\sinθ = 1, \cosθ = 0​, which makes the denominator zero (invalid).
So, sinθ=12\sinθ = \frac{1}{2}​​
θ = 30°
Final Answer
So the correct answer is (c)

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