De Moivre's Theorem: Powers and Roots of Complex Numbers

Convert a complex number between rectangular (a+bi) form and polar (modulus-argument) form, and state De Moivre's theorem for integer powers.

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Te reo Māori terms

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Learning objective overview

Master Teaching Guide coverage for this objective.

Current NZC (2007)
  • No direct alignment recorded
New NZC (2026)
  • NZC26-P4-NUM-NSO-K-Y10-01

Resources

  • No external resource is currently specified.

Terminology

  • De Moivre's theorem
  • Polar form
  • Modulus
  • Argument
  • nth root
  • Roots of unity
  • Argand diagram

Task goals

  • Foundation: Convert a complex number between rectangular (a+bi) form and polar (modulus-argument) form, and state De Moivre's theorem for integer powers.
  • Proficient: Apply De Moivre's theorem to compute a given integer power of a complex number expressed in polar form, simplifying the result back to rectangular form where required.
  • Excellence: Use De Moivre's theorem to find all n distinct nth roots of a complex number (including roots of unity) and represent them on an Argand diagram, or use the theorem to derive a trigonometric multiple-angle identity.

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De Moivre's Theorem: Powers and Roots of Complex Numbers

De Moivre's Theorem: Powers and Roots of Complex Numbers

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