Pythagoras theorem
- Check it is a right triangle.
- Square the shorter sides and add.
- Square root to find the hypotenuse.
Answer: 5² + 12² = 13², so hypotenuse is 13
📐 Geometry & Measures
Pythagoras
Learn pythagoras with a GCSE-style explanation, help guide, worked example, practice question and flashcards.
Global XP
Level 10 / 100 XP
1. Explanation
Key idea
- Pythagoras is part of geometry and appears often in KS3–GCSE maths.
- In a right triangle, a² + b² = c².
- Use the worked model, help guide, interactive question and flashcards to practise pythagoras until the steps feel automatic.
Real-life examples
- Shopping, sport, travel, science, design and everyday decisions all use this skill.
2. Visual
Pythagoras learning map
Understand the key idea → follow the help guide → practise a question → check your method → build speed with flashcards.
3. Help guide
How to tackle Pythagoras
- Learn the rule: In a right triangle, a² + b² = c².
- Worked model: Check it is a right triangle. Square the shorter sides and add. Square root to find the hypotenuse.
- Try the interactive question without looking at the answer first.
- Use the flashcards to test the rule, the method and a common check.
4. Worked examples
Step-by-step working
5. Interactive questions
Try it yourself
A right triangle has shorter sides 3 cm and 4 cm. Find the hypotenuse.
6. Flashcards
Master quick recall
Flip each card, then choose whether you know it or need more practice.
0 mastered
FrontRule for Pythagoras
BackIn a right triangle, a² + b² = c².
FrontExample answer: A right triangle has shorter sides 3 cm and 4 cm. Find the hypotenuse.
Back3² + 4² = 9 + 16 = 25, so c = √25 = 5 cm.
FrontCommon check for Pythagoras
BackCheck units/notation, compare with an estimate, and make sure the answer matches the question.
7. Finish
Complete this topic
When you have read the examples, tried the question and reviewed flashcards, claim your topic completion XP.