The general value of the real angle θ, which satisfies the equation, (cosθ+isinθ)(cos2θ+isin2θ)...(cosnθ+isinnθ)=1 is given by, (assuming k is an integer)
A
2kπn+2
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B
4kπn(n+1)
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C
4kπn+1
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D
6kπn(n+1)
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Solution
The correct option is B4kπn(n+1) Using De Moivre's formula eiθ⋅ei2θ⋯einθ=1⇒eiθn(n+1)2=1⇒n(n+1)θ2=2kπ,k∈I⇒θ=4kπn(n+1),k∈I