Dilations

The algebraic representation shown is used to dilate a quadrilateral with vertices A(-2,8) B(-2,0) C(12,0) and D(6,8).

(x,y) → (½x,½y)

What are the new coordinates of the vertices of A'B'C'?

• A' (-1,4) B' (-1,0) C'(6,0) D'(3,4)

• A' (1,4) B' (1,0) C'(-6,0) D'(-3,4)

• A' (1,-4) B' (1,0) C'(-6,0) D'(-3,-4)

• A' (-1,-4) B' (-1,0) C'(6,0) D'(3,-4)

• A

• B

• C

• D

Triangle KLM has vertices K(5,4) L(-3,7) and M(2,13). Triangle KLM is dilated by a scale factor of 1.5 with the origin as the center of dilaton. The image of Triangle KLM after this dilationis Triangle K'L'M'. What are the coordinates of L' ?

• (-4.5,10.5)

• (-1.5,8.5)

• (-1.5,3.5)

• (0,0)

Triangle EFG has vertices E(3,8) F(10,6) and G(8,2). Triangle EFG is dilated by a scale factor of ½ with the origin as the center of dilaton. The image of Triangle EFG after this dilation is Triangle E'F'G'. What are the coordinates of E' ?

• (1.5,4)

• (5,3)

• (4,1)

• Not here

• A

• B

• C

• D

Quadrilateral WXYZ has vertices W(0,8) X(8,0) Y(4,0) and Z(0,4). Quadrilateral WXYZ is dilated by a scale factor of ¼ with the origin as the center of dilaton. The image of Quadrilateral WXYZ after this dilation is Quadrilateral W'X'Y'Z'. What are the coordinates of Y' ?

• (0,4)

• (4,0)

• (1,0)

• (0,1)

• A

• B

• C

• D

What is the definition of dilations ,in mathematical terms?

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

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.

In a dilation what mathematical operation is used with the scale factor?

• addition 
• subtraction 
• multiplication 
• division