Find the hypotenuse or a missing leg of a right triangle from the other two sides.
Understanding the pythagorean theorem calculation
The Pythagorean theorem links the sides of a right triangle: a² + b² = c². Choose whether to solve for the hypotenuse or a leg, enter the two known sides, and read the answer.
Useful in construction, navigation and geometry.
Try it with these numbers
On the values this calculator opens with, the result is 5. Alongside it, a² + b² comes out at 25. Change any field and every figure updates as you type.
How to use it
- Choose to solve for the hypotenuse or a leg.
- Enter the two known sides.
- Read the missing side length.
The calculation
hypotenuse c = √(a² + b²)
leg a = √(c² − b²)
Frequently asked questions
What is the Pythagorean theorem?
In a right triangle, the square of the hypotenuse equals the sum of the squares of the other two sides (a² + b² = c²).
How do I find a leg?
Rearrange to a = √(c² − b²). The hypotenuse must be the longest side.
Does it only work for right triangles?
Yes — the theorem applies only to triangles with a 90° angle.