Key learning points

1. The sum of the squares of the two shorter sides equals the square of the longest side.
2. The difference between the squares of the longest and known shorter sides is the square of the remaining side.
3. A calculator can perform these calculations efficiently.
4. Rounding gives a less accurate answer so there might be times you wish to leave your answer with an operator.

Common misconception

Keywords

• Right-angled triangle - A right-angled triangle has exactly one 90° interior angle.

• Hypotenuse - A hypotenuse is the side of the right-angle triangle which is opposite the right-angle.

• Pythagoras’ theorem - Pythagoras’ theorem shows that the sum of the squares of the two shorter sides of a right-angled triangle is equal to the square of its longest side (the hypotenuse).