SOLUTION: 21-20i find square root of complex no.

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Question 554019: 21-20i find square root of complex no.
Answer by Alan3354(69443) About Me  (Show Source):
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21-20i find square root of complex no.
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z = 21-20i
angle A = arcsin(-20/29) = arctan(-20/21) =~ 316.4 degs
r+=+sqrt%2821%5E2+%2B+20%5E2%29+=+29
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z = 29cis(A)
sqrt(z) = sqrt(29)*cis(A/2)
= -5 + 2i