How_To_Be_Good_At_Math

GEOMETRY • REFLECTION 261

Make a reflection pattern

You can use reflection to make symmetrical

patterns. Draw a horizontal and a vertical

line on grid paper to make four quadrants,

and copy this design into the first quadrant.

Then reflect it horizontally and vertically into

each quadrant to complete the pattern.

TRY IT OUT

Count the

squares from

A to the line of

reflection. Now

count the same

number of squares

on the other side

of the line and

mark the point A’.

Let’s try

reflecting a

triangle. First, draw

a triangle on grid

or dot paper. Label

the vertices A, B,

and C. Now draw

a vertical line of

reflection.

Answer on page 320

Each point on the

image is the same

distance from the line

of reflection as the

pre-image.

Drawing reflections

It’s easier to draw reflections

using grid or dot paper,

which will help you to place

the reflection accurately.

C

B

A A’

Vertical

line of

reflection

C

B

A

Finally, draw

lines to join

points A’, B’, and C’.

You now have a

new triangle that is

a reflection of

triangle ABC.

Do the same

for the other

two vertices of the

triangle, marking

the new points B’

and C’.

The line between the

two points crosses

the line of reflection

at a right angle

C

B B’

C’

A A’

C

B B’

C’

A A’

260_261_Reflection.indd 261 29/02/2016 18:57