The formula this calculator uses
Pythagorean Theorem Calculator
a² + b² = c²
c = √(a² + b²)
a = √(c² − b²)
Example: a=3, b=4 → c=5 (classic 3-4-5 triangle)
The Pythagorean theorem
Named after the ancient Greek mathematician Pythagoras, the theorem is one of the most useful relationships in geometry, construction, navigation, and physics. Any time you know two sides of a right triangle you can find the third.
How to use this calculator
- Enter the required values in the fields above.
- Results update automatically as you type.
- Adjust any input to explore different scenarios.
Frequently asked questions
What is the hypotenuse?
The hypotenuse is the longest side of a right triangle and is opposite the right angle.
Does the theorem work only for right triangles?
Yes. The relationship a² + b² = c² holds exclusively for right-angled triangles.
Can sides be decimals?
Yes. The formula works with any positive real numbers.
What are Pythagorean triples?
Integer solutions such as 3-4-5, 5-12-13, 8-15-17 that satisfy the theorem exactly.