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Find real such that 3+21−2 is purely real. |
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Answer» ong>Answer: MATHS Find real θ such that 1−2isinθ 3+2isinθ
is purely real. Share Study later ANSWER 1−2isinθ 3+2isinθ
= (1+2isinθ)(1−2isinθ) (3+2isinθ)(1+2isinθ)
= 1−4i sin 2 θ 3+2isinθ+6isinθ+4i 2 sin 2 θ
= 1+4sin 2 θ 3+8isinθ−4sin 2 θ
= 1+4sin 2 θ 3−4sin 2 θ+8isinθ
8sinθ=0⇒sinθ=0 θ=nπ |
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