Dilations

The table describes two dilations with the center of dilation at the origin. Which rule describes each dilation? Move the correct answer to each box in the table. Not all answers will be used.

a

b

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TEKS 8.3C

Dilate the figure by a scale factor of 3 with the origin as the center of dilation. What are the coordinates of the image?
A(3,3) B(6,6) C(9,3)

• A'(9,9) B'(18,18) C'(27,9)
• A'(6,6) B'(9,9) C'(12,6)
• A'(0,0) B'(3,3) C'(6,0)
• A'(1,1) B'(2,2) C'(3,1)

The point (8, 12) was dilated to become point (2, 3). What was the scale factor?

• ½
• ¼
• 4
• 2

Dilate Point B by a scale factor of 1/2

• (1.5,-4)
• (-1.5,1)
• (-1,-1.5)
• (-2,-2)

The red triangle has been dilated by a scale factor of 1/4, which triangle is it's new image? 

• green triangle 
• red triangle 
• black triangle
• none of these 

A scale factor of less than one means

• that the image will be larger than the pre-image.
• That the image will be the same as the pre-image.
• That you need to subtract that amount off  of each side.
• That the image will be a reduction of the pre-image.

What is the definition of dilations ,in mathematical terms?

• to make larger or smaller
• to make larger
• all of the above
• to make smaller

Does the image show a Dilation?

• Yes
• No

Rectangle ABCD is dilated so that the coordinates of C' are (2, -1).  What could be the dilation rule?

• (-2x, +1y)
• (1/2 x, 1/2 y)
• (2x, 2y)
• (x - 2, y - 1)

Dilation rules use ______________ to change the ___________ of a shape. 

• addition; location
• division; direction
• subtraction; orientation
• multiplication; size