Solve for any side of a right triangle using a² + b² = c². Find the hypotenuse or either leg — with full working, angle calculations, and Pythagorean triple detection.
Enter Two Known Sides
Leave the unknown side blank
Unknown Side
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Side a
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Side b
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Hypotenuse c
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Area
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Enter any two sides
a² + b² = c² — enter two values, find the third.
Common Pythagorean Triples
a
b
c
3
4
5
5
12
13
8
15
17
7
24
25
6
8
10
9
40
41
Frequently Asked Questions
What is the Pythagorean theorem?
In a right triangle, the square of the hypotenuse (longest side) equals the sum of squares of the other two legs: a² + b² = c². It only works for right triangles.
What is a Pythagorean triple?
A Pythagorean triple is a set of three positive integers {a, b, c} where a² + b² = c². The most famous is {3, 4, 5}. Multiples also work: {6, 8, 10}, {9, 12, 15}, etc.