Page 78 - Math Course 2 (Book 2)

Transformations: Reflected Images

MO. 9 - L2b point of symmetry
For some figures, a point can be found that is a
Recognizing Lines of common point of reflection for all points on a
figure. This common point of reflection is called a
Symmetry point of symmetry.

Vocabulary A-Z F no points of
symmetry
Let us learn some vocabulary

isometry P P

A transformation that is invariant with respect to
distance. That is, the distance between any two
points in the pre-image must be the same as the points of
distance between the images of the two points. symmetry at P
Y

Let’s Begin
X U’

Z P

Z’ Use Reflections
U X’
Example

Y’

Line of symmetry TABLE TENNIS
Some figures can be folded so that the two halves During a game of table tennis, Dipa decides that
match exactly. The fold is a line of reflection called she wants to hit the ball so that it strikes her side
a line of symmetry. of the table and then just clears the net. Describe
how she should hit the ball using reflections.
None One
desired position
F of ball →

net →
Two More than Two

She should mentally reflect the
desired position of the ball in
Answer the line of the table and aim
toward the reflected image
under the table.

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