If 10sin2θ + 6cos2θ = 7, 0<θ<90° , the find the value of tanθ.
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Correct answer: C
Explanation
The correct answer is option 3 i.e.
10sin2θ + 6cos2θ = 7
⇒ 10sin2θ + 6(1 - sin2θ) = 7 [∵ cos2θ = 1 - sin2θ]
⇒ 10sin2θ + 6 - 6sin2θ = 7
⇒ 4sin2θ = 1
⇒ sin2θ = 1/4
⇒ sinθ = 1/2 = sin 30°
⇒ θ = 30°
⇒ tanθ = tan 30° = 1/√3
Therefore, the value of tanθ is 1/√3.