De Moivre’s Theorem Calculator
De Moivre’s theorem raises the modulus to the power and multiplies the angle: (1 + i)³ = -2 + 2i.
-2 + 2i
- |z| = r
- 1.414213562
- arg z (degrees)
- 45
- |zⁿ| = r^3
- 2.828427125
| k | Root | Angle (°) |
|---|---|---|
| 0 | 1.0842151 + 0.29051456i | 15 |
| 1 | -0.79370053 + 0.79370053i | 135 |
| 2 | -0.29051456 − 1.0842151i | 255 |
Step-by-step solution
- De Moivre: [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)], 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:
- De Moivre: [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)], k = 0 … n − 1
arg z (degrees): 45 · |zⁿ| = r^3: 2.828427125
| k | Root | Angle (°) |
|---|---|---|
| 0 | 1.0842151 + 0.29051456i | 15 |
| 1 | -0.79370053 + 0.79370053i | 135 |
| 2 | -0.29051456 − 1.0842151i | 255 |
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.
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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/