Pythagorean Theorem Calculator
Solve a right triangle: find the hypotenuse or a missing leg.
Missing side
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Side found
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Triangle area
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Perimeter
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Acute angles
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Results update as you type.
About this calculator
The Pythagorean theorem states that in a right triangle a² + b² = c², where c is the hypotenuse (the side opposite the right angle). This calculator solves for the hypotenuse from two legs, or for a missing leg from the hypotenuse and one leg.
Frequently asked questions
What is the Pythagorean theorem?
For a right triangle, a² + b² = c², where c is the hypotenuse. A 3-4 right triangle has hypotenuse √(9 + 16) = 5.
How do you find a missing leg?
Rearrange to a = √(c² − b²). The leg must be shorter than the hypotenuse, so the hypotenuse value must be the largest side.
Results are estimates for general guidance only, not financial, medical or tax advice.