Warm Up

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Warm Up Tuesday, August 19th
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Dilations in the Coordinate Plane

• Tuesday, August, 19th

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Dilations

• What is a dilation?
• A transformation that changes the size of a
  figure.
• What are two types of dilations?
• Enlargement
• Reduction
• The point of projection is called the center of
  dilation
• The amount of change is written as a ratio and is
  called a scale factor.

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Dilations

• In the coordinate plane, the center of dilation
  is the origin.
• To find the new coordinates, multiply the
  original coordinates by the scale factor.

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Steps to Follow

1. Plot the given points.
2. Multiply each coordinate by the scale factor.
3. Plot the image points.
4. State the coordinates of the dilation.

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Given the vertices of the triangle, find a
dilation by a scale factor of 3.
B
C

• A (1,2)
• B (3,3)
• C (1,3)

A (3,6)
A
B (9,9)
C
B
C (3,9)
A
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Given the vertices of the rectangle, find a
dilation by a scale factor of 2/3.

• A (-6,-3)
• B (-6,3)
• C (6,3)
• D (6,-3)

A (-4,-2)
B (-4,2)
C (4,2)
B
C
D (4,-2)
B
C
A
D
A
D
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Practice with Dilations

• http//www.regentsprep.org/Regents/math/geometry/G
  T3/PracCoD.htm

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Homework

• Work Packet Dilations