Dilations

Dilations

Dilations will enlarge or reduce your image on the coordinate plane. 

Remember!

The rule for a dilation is
  $(x,y)→(kx,ky)$  


k is your scale factor and we are multiplying. 

If |k| > 1, it is an ENLARGEMENT (stretch).
If 0<|k| < 1, it is a REDUCTION (shrink).

Multiple Choice

Warm Up 1/28/21

A scale factor of 1/2 reduces a figure.

• True

• False

Open Ended

Explain why the answer to the warm up was true.

" A scale factor of 1/2 reduces a figure."

Multiple Choice

When the dilation has a scale factor greater than one, the dilation is an enlargement.

• True

• False

Multiple Choice

When the scale factor of a dilation is less than one, the dilation is a reduction.

• True

• False

Fill in the Blanks

If a dilation has the rule
 $(x,y)→(2.5x,2.5y)$  what is the scale factor?

Multiple Choice

If a dilation has the rule
 $(x,y)→(2.5x,2.5y)$  what type of dilation is this?

• enlargement

• reduction (shrink)

Multiple Choice

A polygon is graphed on a coordinate grid with (x,y) representing the location of a certain point on the polygon. The polygon is transformed using the rule (x, y)→(ax, ay). Which statement must be true?

• If a is greater than 1, the image of the polygon is congruent to the polygon.

• If a is between 0 and 1, the image of the polygon is congruent to the polygon.

• If a is greater than 1, the image of the polygon is smaller than the polygon.

• If a is between 0 and 1, the image of the polygon is smaller than the polygon.

Multiple Choice

If the triangle ABC is dilated using a scale factor of k=2, what will be the coordinates of A' after the transformation?(Click the picture to zoom in on it)

• A'(1.5, -1.5)

• A' (-6, 6)

Multiple Choice

Click image to enlarge

• A

• B

• C

• D

Multiple Choice

Click image to enlarge

• A

• B

• C

• D

Multiple Choice

Click image to enlarge

• A

• B

• C

• D

Poll

How well do you understand dilations?