This introduction covers From Flat to 3D 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 1 of 5 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.
From Flat to 3D
Ever wondered how to find the diagonal of a box, or the space diagonal of a room? Use Pythagoras TWICE! First find the diagonal of the base (2D), then use that as one side of a new right triangle going up (3D). It's the same a² + b² = c² logic, just used in layers.
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