Length of the hypotenuse
I can use Pythagoras' theorem to find the length of the hypotenuse.
Length of the hypotenuse
I can use Pythagoras' theorem to find the length of the hypotenuse.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- The sum of the squares of the two shorter sides equals the square of the longest side.
- The longest side is always opposite the right angle.
- A calculator can perform these calculations efficiently.
- Priority of operations makes the order clear.
Keywords
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).
Hypotenuse - A hypotenuse is the side of the right-angle triangle which is opposite the right-angle.
Right-angled triangle - A right-angled triangle has exactly one 90° interior angle.
Common misconception
Pythagorean triples can be a trio of any rational numbers that, when constructed into a triangle, always produces a right-angled triangle.
Pythagorean triples are conventionally a trio of integer side lengths of a right-angled triangle, such as the 3, 4, 5 triangle. Other, similar triangles can be generated from Pythagorean triples, whose side lengths are rational, such as 0.3, 0.4, 0.5
To help you plan your year 9 maths lesson on: Length of the hypotenuse, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 9 maths lesson on: Length of the hypotenuse, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 3 maths lessons from the Geometrical properties: similarity and Pythagoras' theorem unit, dive into the full secondary maths curriculum, or learn more about lesson planning.
Licence
Starter quiz
6 Questions



Exit quiz
6 Questions





