Mark the Correct alternative in the following:

If a = cos θ + i sin θ, then

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If i² = - 1, then the sum i + i² + i³ + …. upto 1000 terms is equal to

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If then the value of arg(z) is

Mark the Correct alternative in the following:

If (1 + i) (1 + 2i) (1 + 3i) … (1 + ni) = a + i b, then 2 . 5. 10 . 17 ……..(1 + n²) =

Mark the Correct alternative in the following:

If then x² + y² is equal to