7th Grade · Geometry
Pyramid
7.G.A.3
Definition
A 3D solid with one polygonal base and triangular lateral faces that meet at a single point called the apex. Named by the shape of the base.
Examples
- A square pyramid has 1 square base + 4 triangular faces = 5 faces, 5 vertices, 8 edges.
- A triangular pyramid (tetrahedron) has 4 triangular faces, 4 vertices, 6 edges.
Key rule
Prism has 2 bases and no apex; pyramid has 1 base and 1 apex.
Memory hook
One base, triangles meeting at a point.