# Pythagoras Theorem Calculator

This is an online Pythagoras Theorem calculator that helps you find out the length of any side of a right triangle, provided you know the lengths of the other two sides. Besides the calculator, it also provides you with information about Pythagoras Theorem.

## What is Pythagoras Theorem?

The Pythagorean Theorem (aka. Pythagoras’ theorem) describes the relations between the three sides of a right triangle. It states that the sum of the squares of the shorter sides of a right triangle equals the square of the hypotenuse. Here is the formula:

`a`

^{2} + b^{2} = c^{2}

where a and b are the length of the two shorter sides and c is the length of the hypotenuse.

The theorem was named after the ancient Greek philosopher and mathematician Pythagoras, who lived in the sixth century BC.

## Pythagoras Theorem example

Let’s solve the triangle below. Find *x*.

The triangle is a right-angled triangle. Therefore, we can find the length x using the Pythagoras Theorem.

x is the hypotenuse. We first start by writing the equation: `9`

^{2} + 12^{2} = x^{2}

We can then use algebra to find x:

9^{2} + 12^{2} = x^{2}

225 = `x`

^{2}

**x = 15**

## How to use the Pythagoras Theorem calculator?

- Under the Find box, select the side that you want to find out (a / b / c).
- Input the length of the two sides that you have. For example, suppose you want to find c, enter the value of a and b.
- The result is automatically calculated and displayed in the field below.