How_To_Be_Good_At_Math

GEOMETRY • REFLECTIVE SYMMETRY 257

Lines of symmetry in 2D shapes

Here are the lines of symmetry in some common 2D shapes.

Number symmetry

Look at each of these numbers. How

many lines of symmetry does each one

have? The answer will either be one,

two, or none.

TRY IT OUT

Isosceles triangle

One line of symmetry

Regular pentagon

Five lines of symmetry

Every straight

line that

divides a circle

through its

centre is a

line of

symmetry

Circle

Unlimited lines of symmetry

This shell shape

has no lines of

symmetry

Asymmetry

Some shapes are asymmetrical, which means they

don’t have any lines of symmetry. You can’t draw a

line anywhere on them to make a mirror image.

1

1

Rectangle

Two lines of symmetry

1

2

Regular hexagon

Six lines of symmetry

1 2

3

4

5

6

2

3

4

5

Equilateral triangle

Three lines of symmetry

1

2

3

This seahorse

shape also has

no lines of

symmetry

Answers on page 320

256_257_Reflective_Symmetry.indd 257 29/02/2016 18:06