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Pythagorean Theorem Calculator

Use our free Pythagorean theorem calculator to find the missing side length of a right triangle. Enter any two side lengths and instantly compute the third using a² + b² = c².

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Side A (a)

Side B (b)

Formula

The Pythagorean theorem states that in a right triangle, the square of the hypotenuse (c) equals the sum of the squares of the other two sides (a and b): a² + b² = c².

a² + b² = c²

Percentage: The percentage value you want to apply

Number: The original number or value

Result: The calculated result

How It Works

1Enter the length of side A (a).
2Enter the length of side B (b).
3Click Calculate to find the hypotenuse (c).
4c = √(a² + b²).

Examples

Right triangle with sides 3 and 4

1.Enter sideA = 3, sideB = 4.
2.c² = 3² + 4² = 9 + 16 = 25.
3.c = √25 = 5.

Result: 5.0000 units

Right triangle with sides 6 and 8

1.Enter sideA = 6, sideB = 8.
2.c² = 6² + 8² = 36 + 64 = 100.
3.c = √100 = 10.

Result: 10.0000 units

Frequently Asked Questions

The Pythagorean theorem states that a² + b² = c² for a right triangle, where c is the hypotenuse and a and b are the legs.

Yes. Rearrange the formula: a = √(c² - b²) or b = √(c² - a²). Enter the hypotenuse as one input and the known leg as the other.

No. The Pythagorean theorem only applies to right triangles (triangles with a 90° angle).

Named after the Greek mathematician Pythagoras, this theorem has been known for thousands of years and is one of the most fundamental in geometry.

Yes. All three sides must be in the same unit. The result will be in that same unit.

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CalculateMe Team

Last updated: 2026-07-13

Pythagorean Theorem Calculator - a² + b² = c² | CalculateMe | CalculateMe