Hypotenuse Calculator
Pythagorean theorem: a² + b² = c². Find the hypotenuse or a missing leg.
Inputs
For right triangles only
Result
Enter values and click calculate.
The Pythagorean theorem
For any right triangle with legs a and b and hypotenuse c, a² + b² = c². The hypotenuse is the longest side, opposite the right angle. Common Pythagorean triples include (3, 4, 5), (5, 12, 13), and (8, 15, 17).
Frequently Asked Questions
What is the hypotenuse?▾
The hypotenuse is the longest side of a right triangle, opposite the 90° angle. By the Pythagorean theorem, c = √(a² + b²).
How do I find a leg if I know the hypotenuse?▾
Rearrange the Pythagorean theorem: missing leg = √(c² − known leg²). The known leg must be smaller than the hypotenuse.
What are Pythagorean triples?▾
Sets of three positive integers (a, b, c) with a² + b² = c². Common examples: (3, 4, 5), (5, 12, 13), (7, 24, 25), (8, 15, 17).
Does the Pythagorean theorem only work for right triangles?▾
Yes. For other triangles, use the Law of Cosines, which generalizes the formula to any triangle.