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Section 6.6 De Moivre's Theorem and nth Roots
be a complex number.
is the trigonometric (or
polar) form of where
Let
θ
r
(a, b) •
Find the trigonometric form of
•
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De Moivre's Theorem
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The nth Root of a Complex Number
Solve each.
•
•(1, 0)
•
•
• • • • •
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1. Find the 3 cube roots of −27.
2. Find the cube roots of
First find the trigonometric form of
Then use De Moivre's Theorem to raise it to
the one-third power.
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