How_To_Be_Good_At_Math

GEOMETRY • 3D SHAPES 223

Face

The surface of a 3D object is made of

2D shapes called faces. Faces can be flat

or curved.

Edge

An edge is formed when two or

more faces of a 3D shape meet.

Vertex

The point where two or more edges

meet is called a vertex. The plural of

“vertex” is “vertices”.

This shape

has seven

faces

This shape

has 10

vertices

This shape

has 15

edges

REAL WORLD MATHS

It’s a 3D world

Anything that has length, width, and height is

3D. Even a thin object, like a sheet of paper

that’s less than 1 mm thick, has some height, so

it’s 3D, too. A complicated shape, like this plant

in a pot, is also 3D, even though it’s tricky to

measure its different dimensions.

Answers on page 320

TRY IT OUT

Find the faces

Can you count the number of faces, edges, and

vertices on this 3D shape?

222_223_3D_What_is_3D_shape.indd 223 29/02/2016 18:05