What is the Pythagorean theorem?

For a right triangle with legs a and b and hypotenuse c: a² + b² = c². The hypotenuse is always the longest side, opposite the 90° angle.

What is a Pythagorean triple?

Three integers that satisfy a² + b² = c², like 3-4-5, 5-12-13, or 8-15-17. These form perfect right triangles.

Pythagorean Theorem Calculator

Enter two sides of a right triangle to find the third side, angles, area, and perimeter.

Solve any right triangle using the Pythagorean theorem (a² + b² = c²). Enter any two sides to find the third. Also calculates triangle area, perimeter, and both acute angles.

Last reviewed: April 2026Report an error

Solve for

Side a (leg)

Side b (leg)

Side C

a = 3, b = 4, c = 5. Area: 6 sq units. Angles: A=36.9°, B=53.1°, C=90°.

Sides (a, b, c)

3, 4, 5

Area

Angles A / B

36.9° / 53.1°

How to Use This Pythagorean Calculator

Enter any two known sides (a, b for legs; c for hypotenuse).
Leave the third side blank.
Read the missing side, triangle area, perimeter, and both acute angles.

Frequently Asked Questions

: For a right triangle with legs a and b and hypotenuse c: a² + b² = c². The hypotenuse is always the longest side, opposite the 90° angle.
: Three integers that satisfy a² + b² = c², like 3-4-5, 5-12-13, or 8-15-17. These form perfect right triangles.

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Pythagorean Theorem Calculator

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