Dilation - PowerPoint Presentation

Slide1

Dilation

Distributive property

and

SimilaritySlide2

Vocabulary

Dilation: Increases or decreases the size of an object by a scale factor ( r ), with out changing the shape of the object.

Scale Factor: Ratio of the pre-image to the image; the factor that is used to increase or decrease the size of an object.

Distributive Property: Used to multiply a single term to multiple terms.

Similarity: When objects have the same shape, but may be different sizes. Slide3

With scale factor

r

…

A

figure

is reduced in size when ________________. A figure is enlarged when ____________. When _________ the figure is congruent.

http://www.mathopenref.com/dilate.htmlSlide4

G

iven the point

find

the location of the dilated point

when

Note: The scale factor will need to be distributed to the x and y of our ordered pair.

So, A’ (6,15)Slide5

Given point A(-2,3), predict the location of A' when A is dilated

by

scale factor

r=4.

Note: The scale factor will need to be distributed to the x and y of our ordered pair.

So, A’ (-8, 12)Slide6

Determine the scale factor used when A (4, 10) and A’ (2,5)

Since r was distributed (multiplied) to A and the result was A’ we can use division to find r.

So,

and

Thus, r =

 Slide7

Determine the scale factor used when A (3, 5) and A’ (9,15)

Since r was distributed (multiplied) to A and the result was A’ we can use division to find r.

So,

Thus, r=3

 Slide8

T

riangle

has coordinates

, and

and is

being dilated from the origin with

What are the coordinates of triangle

?

A'= (4 · 2 , 4 · 3) = (8,12)

B'= (4 · (-3), 4 · 4) = (-12,16)C'= (4 · 5, 4 · 7) = (20,28)

Note: The scale factor will need to be distributed to the x and y of each ordered pair.