GCSE Maths Revision Guide
Pythagoras' Theorem
Find missing sides in right-angled triangles. This free GCSE Maths module combines short explanations, worked examples, flashcard-style recall, and timed practice so students can revise the topic without creating an account.
Foundation Skills
Pythagoras' Theorem
In a right-angled triangle, the square of the hypotenuse equals the sum of the squares of the other two sides.
Formula: a² + b² = c²
Example: a=3, b=4: c² = 9 + 16 = 25 c = √25 = 5
Finding the Hypotenuse
Square both sides, add, then square root.
Formula: c = √(a² + b²)
Example: a=5, b=12: c = √(25 + 144) = √169 = 13
Higher Skills
Finding a Shorter Side
Rearrange: a² = c² − b²
Formula: a = √(c² − b²)
Example: c=10, b=6: a = √(100 − 36) = √64 = 8
3D Pythagoras
Find the space diagonal: d² = a² + b² + c².
Formula: d = √(a² + b² + c²)
Example: Cuboid 3×4×12: d = √(9+16+144) = √169 = 13