ForHosting KIT · Math

De Moivre Theorem Power Calculator for Complex Numbers

Cubing a complex number with modulus 2 and argument 30° gives modulus 8 and argument 90°, which is a real part of 0 and an imaginary part of 8. Enter modulus, argument and power in degrees or radians; zero and negative powers work where defined. Free in your browser.

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If you enter
Modulus
2
Argument
30
Power
3
Angle unit
Degrees
You get
Modulus
8
Argument
90
Real
0
Imaginary
8

This De Moivre theorem power calculator raises a complex number written in polar form to any supported integer power. Enter the non-negative modulus, the argument, and the exponent, then choose degrees or radians. The calculator applies the theorem directly and returns the new modulus and argument together with the rectangular real and imaginary components. It handles zero and negative integer powers when they are mathematically defined, making it useful for homework checks, engineering calculations, and software tests without requiring you to convert the input to rectangular form first.

Enter a complex number in polar form

A complex number in polar form is described by a modulus and an argument. The modulus is the distance from the origin, so this calculator requires it to be zero or positive. The argument gives the direction of the number and may be entered in degrees or radians.

Select the unit that matches your source instead of converting the angle beforehand. For example, a modulus of 2 and an argument of 30 degrees represents the same point as a modulus of 2 and an argument of pi divided by 6 radians. The power must be an integer because this capability applies the integer-power form of De Moivre's theorem.

Positive powers multiply the argument while expanding or shrinking the modulus. A power of zero returns the multiplicative identity for every nonzero input. Negative powers compute reciprocals, so the calculator rejects a zero modulus paired with a negative exponent.

Angles are not forced into a principal interval; preserving the multiplied argument makes every step of the theorem visible and avoids hiding complete rotations that may matter in a derivation.

Understand the De Moivre calculation

De Moivre's theorem states that a polar complex number of the form r times cosine theta plus i sine theta, raised to an integer n, becomes r to the power n times cosine n theta plus i sine n theta. The calculator therefore performs two central operations: it raises the modulus to the selected integer power and multiplies the argument by that power. It then evaluates cosine and sine at the resulting angle to obtain the rectangular components.

The real component is the new modulus multiplied by cosine of the new argument, and the imaginary component is the new modulus multiplied by sine of that argument. The returned polar expression shows the same new modulus and argument used for the rectangular conversion. Because trigonometric functions are periodic, an argument such as 450 degrees may describe the same direction as 90 degrees; the unnormalized value is still correct and more directly records the multiplication performed by the theorem.

Read and verify the result

The response gives the resulting modulus, argument, selected angle unit, real component, imaginary component, a readable polar expression, and the method name. Use the modulus and argument when continuing a polar-form calculation, or use real and imaginary when you need the conventional a plus bi form. A quick verification is to check that the square root of real squared plus imaginary squared agrees with the returned modulus, allowing for ordinary floating-point rounding.

You can also divide the output argument by the power to recover the input argument when the power is nonzero. Negative powers often produce a fractional modulus and reverse the sign of the angle when the original angle is positive. Inputs are not sent to a third-party service, and the algorithm uses no randomness, current time, or network data.

Check complex-number homework

Confirm the polar and rectangular results of an integer-power exercise while keeping the theorem's multiplied angle visible.

Validate engineering calculations

Raise phasors in polar form and obtain deterministic real and imaginary components for downstream checks.

What formula does the calculator use?

It uses [r(cos theta + i sin theta)]^n = r^n[cos(n theta) + i sin(n theta)] for an integer n.

Are negative powers supported?

Yes, provided the modulus is not zero. A negative power takes the reciprocal of the powered modulus and multiplies the angle normally.

Why is the returned argument larger than one rotation?

The calculator returns the direct product n times theta rather than normalizing it, which preserves the steps of De Moivre's theorem. Coterminal angles represent the same direction.

What does it cost?

The browser calculator can run the same pure calculation locally.

How do I cube a complex number with modulus 2 and argument 30 degrees?

Raise the modulus to the power 3 and multiply the argument by 3: the result has modulus 8 and argument 90 degrees. In rectangular form that is a real part of 0 and an imaginary part of 8.

Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.

POSThttps://api.kit.forhosting.com/trig/demoivre-power

Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.

curl -X POST https://api.kit.forhosting.com/trig/demoivre-power \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"modulus":2,"argument":30,"power":3}'
{
  "modulus": 2,
  "argument": 30,
  "power": 3
}
{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "trig.demoivre_power",
  "status": "queued",
  "_links": {
    "result": "/tasks/tsk_…/result"
  }
}

The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.

Per request$0.002

Published price — no tokens, no invented credits. A failed task is never charged.

max_abs_power1000000
HTTPCodeMeaning
401unauthorizedMissing or invalid API key.
402insufficient_balanceYour balance doesn't cover the task price.
404unknown_typeThat task type doesn't exist.
429rate_limitedToo many requests. Use the webhook instead of polling.

Read and verify the result

The API price is $0.002 per request, while the browser version can run the same deterministic calculation locally. Results that overflow or underflow beyond a useful finite representation are rejected instead of returning misleading infinity or invalid JSON values, so callers can adjust the modulus or exponent explicitly.

Create software test fixtures

Generate stable expected values for code that implements complex powers, polar conversion, or trigonometric identities.

Can I enter the argument in radians?

Yes. Set angle_unit to radians; the returned argument will use radians too.

Read the full KIT documentation →