Solve for a missing side using a² + b² = c² with clear steps and unit consistency. Fully client-side — no account, uploads, or remote storage.
Added Apr 26, 2026
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Result
Enter a value for solve for to see your result.
Solves a right triangle with the Pythagorean theorem (a² + b² = c²). Enter two known sides and the tool computes the third, with the full step-by-step working shown.
a² + b² = c²
c = √(3² + 4²) = √(9 + 16) = √25 = 5. The classic 3-4-5 right triangle.
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leg = √(13² − 5²) = √(169 − 25) = √144 = 12. The 5-12-13 Pythagorean triple.
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Result
In any right triangle, the square of the hypotenuse equals the sum of the squares of the other two sides: a² + b² = c². It only applies when one angle is exactly 90°.
Rearrange the formula: a = √(c² − b²). The hypotenuse must be longer than the leg you already know, otherwise the square root is of a negative number and there is no real solution.
A set of three positive integers (a, b, c) that satisfy a² + b² = c². Common triples are 3-4-5, 5-12-13, 8-15-17, and 7-24-25. The tool flags inputs that form one.