http://www.ck12.org Chapter 7. Similarity
Remember that to dilate something in the coordinate plane, multiply each coordinate by the scale factor.
For this dilation, the mapping will be(x,y)→( 1. 5 x, 1. 5 y).
E(− 4 ,− 2 )→( 1. 5 (− 4 ), 1. 5 (− 2 ))→E′(− 6 ,− 3 )
F( 1 , 4 )→( 1. 5 ( 1 ), 1. 5 ( 4 ))→F′( 1. 5 , 6 )
G( 6 , 2 )→( 1. 5 ( 6 ), 1. 5 ( 2 ))→G′( 9 , 3 )
H( 0 ,− 4 )→( 1. 5 ( 0 ), 1. 5 (− 4 ))→H′( 0 ,− 6 )
Watch this video for help with the Examples above.
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/52541CK-12 Foundation: Chapter7DilationintheCoordinatePlaneB
Vocabulary
In the graph above, the blue quadrilateral is the original and the red image is the dilation. Adilationan enlargement
or reduction of a figure that preserves shape but not size. All dilations are similar to the original figure. Similar
figures are the same shape but not necessarily the same size. Thecenter of dilationis the point of reference for the
dilation and thescale factorfor a dilation tells us how much the figure stretches or shrinks.
Guided Practice
GivenAand the scale factor, determine the coordinates of the dilated point,A′. You may assume the center of
dilation is the origin.
1.A( 3 , 9 ),k=^23