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    De Moivre’s Theorem Calculator

    De Moivre’s theorem raises the modulus to the power and multiplies the angle: (1 + i)³ = -2 + 2i.

    z given as:
    zⁿ = z^3

    -2 + 2i

    |z| = r
    1.414213562
    arg z (degrees)
    45
    |zⁿ| = r^3
    2.828427125
    The 3 roots z^(1/3)
    kRootAngle (°)
    01.0842151 + 0.29051456i15
    1-0.79370053 + 0.79370053i135
    2-0.29051456 − 1.0842151i255
    Step-by-step solution
    1. De Moivre: [r(cos θ + i sin θ)]ⁿ = rⁿ(cos nθ + i sin nθ)
    2. Roots: r^(1/n)[cos((θ + 2πk)/n) + i sin((θ + 2πk)/n)], k = 0 … n − 1

    De Moivre’s Theorem Formula

    [r(cos θ + i sin θ)]ⁿ = rⁿ(cos nθ + i sin nθ)

    roots: r^(1/n)[cos((θ + 2πk)/n) + i sin((θ + 2πk)/n)]

    Worked Example

    z = 1 + i with n = 3:

    1. De Moivre: [r(cos θ + i sin θ)]ⁿ = rⁿ(cos nθ + i sin nθ)
    2. Roots: r^(1/n)[cos((θ + 2πk)/n) + i sin((θ + 2πk)/n)], k = 0 … n − 1

    arg z (degrees): 45 · |zⁿ| = r^3: 2.828427125

    The 3 roots z^(1/3)
    kRootAngle (°)
    01.0842151 + 0.29051456i15
    1-0.79370053 + 0.79370053i135
    2-0.29051456 − 1.0842151i255

    GATE tip

    For powers like (1 + i)¹⁰, convert to polar form first: √2∠45°, so the result is 32∠450° = 32i. This is much faster than repeated multiplication.

    More Probability and Complex Variables Calculators

    Frequently asked questions

    How many n-th roots does a complex number have?

    Exactly n distinct roots, equally spaced at 360°/n on a circle of radius r^(1/n).

    What are the cube roots of unity?

    1, −1/2 + (√3/2)i and −1/2 − (√3/2)i; they add up to 0 and multiply to 1.

    Sources

    Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.

    Cite this page

    APA

    Scientific Converters. (2026, October 15). De Moivre’s Theorem Calculator. Retrieved October 25, 2026, from https://scientificconverters.com/calculators/de-moivre-calculator/

    IEEE

    Scientific Converters, "De Moivre’s Theorem Calculator," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/calculators/de-moivre-calculator/

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