# Introducing Pythagoras’ Theorem

**Right-angled triangles**

A **right-angled triangle** has the following features:

- It contains a right angle corner
- The longest side is called the hypotenuse and is opposite the right angle
- The sum of the two other angels in a right angle triangle add up to 90º and are all complementary angles.

**Pythagoras’ Theorem**

The **Pythagoras’ Theorem** states that the square formed on the hypotenuse of a right-angled triangle is identical to the sum of the areas of the squares formed on the other two sides.

This is expressed in the following formula:

*c*² = *a*² + *b*²