This deep dive covers Method: 3D Pythagoras within Pythagoras in 3D for GCSE Mathematics. Revise Pythagoras in 3D in Geometry & Measures for GCSE Mathematics with 12 exam-style questions and 2 flashcards. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 3 of 5 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Method: 3D Pythagoras
1
Identify the right-angled triangles in the 3D shape
2
First Pythagoras: find the base diagonal
3
Second Pythagoras: use base diagonal + height
4
Or use the direct formula: d² = x² + y² + z²
Practice questions for Pythagoras in 3D
A cuboid has length l, width w, and height h. Which formula gives the length of the space diagonal d?
Describe the two-step method for finding the space diagonal of a cuboid with dimensions l, w, and h.
Quick recall flashcards
3D Pythagoras
d² = x² + y² + z² for space diagonal. Or use 2D Pythagoras twice: first on base, then with height.
3D Pythagoras
Use Pythagoras twice: once for base diagonal, once for 3D diagonal