If 7 sin2 θ + 4 cos2 θ = 5 and θ lies in the first quadrant, then what is the value of
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Correct answer: D
Explanation
The correct answer is option 4 i.e. 2(1+√2)
⇒ 7 sin2 θ + 4 cos2 θ = 5
⇒ 3 sin2 θ + 4 sin2 θ + 4 cos2 θ = 5
⇒ 3 sin2 θ = 1
⇒sinθ = 1/ = P/H
B2 = 3 - 1 = 2
B =
⇒ secθ = , tanθ = 1/ , cotθ = and cosθ =
= =
On further rationalization we get,
= = 2(1+√2)