Pythagorean theorem calculator

Find the hypotenuse or a leg of a right triangle (a² + b² = c²).

Hypotenuse c

c²25

How the calculation works

In a right triangle, the square of the hypotenuse equals the sum of the squares of the legs: a² + b² = c². So c = √(a²+b²) and b = √(c²−a²).

What is a 3-4-5 triangle?

A classic right triangle: 3² + 4² = 5² (9 + 16 = 25).

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Updated on June 18, 2026 · by Rafael Rossi · Methodology & sources