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Question
Solve : Sin2θ - 3sin θ + 2 = 0 .
Solution
sin2θ - 3sin θ + 2 = 0
⇒ sin2θ - 2sin θ - sin θ + 2 = 0
⇒ sin θ (sin θ - 2) - 1(sin θ - 2) = 0
⇒ (sin θ - 2)(sin θ - 1) = 0
⇒ sin θ - 2 = 0
⇒ sin θ = 2
sin θ = 2 has no solution for angle θ, as there is no any angle whose sin θ is equal to 2.
⇒ sin θ - 1 = 0
⇒ sin θ = 1
⇒ θ = 90°
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