Can this calculator find a missing leg instead of the hypotenuse?

Yes. Given the hypotenuse and one leg, it rearranges the formula to a = √(c² − b²) to solve for the missing leg instead.

Does the Pythagorean theorem work for any triangle?

No, it only applies to right triangles (one 90° angle). For other triangles, use the law of cosines, available in the Triangle Calculator.

Find a triangle's hypotenuse or a missing leg using the Pythagorean theorem.

How this is calculated

a² + b² = c²

Assumptions used in this calculation

Right triangle only: The formula a² + b² = c² is only valid for right triangles; inputs are assumed to describe a right triangle's sides.

Solves a² + b² = c² for the hypotenuse (given two legs) or a missing leg (given the hypotenuse and one leg).

Worked example

Legs 3 and 4

Result: Hypotenuse = 5

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