Page 70 - Math Course 2 (Book 2)

Transformations in Geometry

MO. 9 - L1b Let’s Begin

Transformations:

Reflections and Dilations
Reflections in a Coordinate Plane

Vocabulary A-Z Example

Let us learn some vocabulary

The vertices of a figure are M(–8, 6), N(5, 9), O(2, 1),
reflection and P(–10, 3). Graph the figure and the image of the
figure after a reflection over the y-axis.
In a reflection, you flip a figure over a line.
To find the coordinates of the vertices of the
line of symmetry image after a reflection over the y-axis, multiply the

In a reflection, you flip a figure over a line. This line x-coordinate by –1 and use the same y-coordinate.
is called a line of symmetry.
opposite
y line of symmetry
same
M (–8, 6) ® (–1 �(–8), 6) ® M‘ (8, 6)
N (5, 9) ® (–1 �5, 9) ® N‘ (–5, 9)
O (2, 1) ® (–1 �2, 1) ® O‘ (–2, 1)
0 x P (–10, 3) ® (–1 �(–10), 3) ® P‘ (10, 3)

Answer

dilation
In a dilation, you enlarge or reduce a figure by a
scale factor with respect to a fixed point.

center
In a dilation, you enlarge or reduce a figure by a
scale factor with respect to a fixed point called the
center.

y

Center 0 x

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