Solve a² + b² = c² for the missing side of a right triangle, given the other two.
For any right triangle, the square of the hypotenuse (the longest side, opposite the right angle) equals the sum of the squares of the other two sides: a² + b² = c². Given any two sides, the third follows directly — add or subtract the squares, then take the square root.
The Pythagorean theorem is a special case of the more general law of cosines, which applies to any triangle. When the angle between two sides happens to be exactly 90°, the cosine term in that general formula drops to zero, leaving exactly a²+b²=c².
A set of three whole numbers that satisfy a²+b²=c² exactly, like 3-4-5 or 5-12-13. They're useful as quick mental-math reference points and show up often in textbook problems.
No — for any triangle without a 90° angle, use the law of cosines instead, which is exactly what our Triangle Calculator does.
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