Pythagoras Calculator
Find Any Side ⚡
Enter any two sides of a right-angled triangle — leave the one you want to find blank. Uses a² + b² = c².
Leave the side you want to find blank
Enter any two sides of a right-angled triangle — leave the one you want to find blank. Uses a² + b² = c².
Leave the side you want to find blank
In any right-angled triangle: a² + b² = c²
Where c is the hypotenuse (opposite the right angle) and a and b are the shorter sides.
Find c: c = √(a² + b²)
Find a: a = √(c² − b²)
Find b: b = √(c² − a²)
What is the hypotenuse?
The hypotenuse is the longest side — always opposite the 90° right angle. It is always c in Pythagoras' theorem.
What is a Pythagorean triple?
A set of three whole numbers satisfying a² + b² = c². Common examples: 3-4-5, 5-12-13, 8-15-17.
Can I use this for any triangle?
No — Pythagoras' theorem only applies to right-angled triangles. For other triangles use the Cosine Rule.