Pythagorean Theorem Calculator
Solve any side of a right triangle: the hypotenuse from two legs, or a missing leg from the hypotenuse — with the triangle's area and perimeter.
Result
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Area —
Perimeter —
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How it works
c = √(a² + b²); missing leg: a = √(c² − b²)Frequently Asked Questions
How do I find the hypotenuse?
Square both legs, add, take the square root: legs of 3 and 4 give √(9+16) = 5 — the most famous triangle in mathematics.
How do I find a missing leg?
Rearrange: leg = √(hypotenuse² − other leg²). The hypotenuse must be the longest side, or there is no valid right triangle.
Where is the Pythagorean theorem used in real life?
Everywhere distances matter: diagonal of a TV or room, ladder placement, roof rafter lengths, navigation, and the distance formula in coordinate geometry is the theorem in disguise.