Pythagoras' theorem can also be used to solve 3D problems. You often need to use Pythagoras' theorem more than once in each problem as we create extra right-angled triangles in the 3D shapes.

A 3D shape with regular polygonal faces, meeting at equal angles, is a platonic solid ... When the cross-section is a triangle, the prism is called a triangular prism. When the cross-section ...