A dilation is a type of transformation that changes the size of the image. The scale factor, sometimes called the scalar factor, measures how much larger or smaller the image is. Below is a picture of a dilation with a scale factor of 2. This means that the image, A', is twice as large as the pre-image A. Like other transformations, prime notation is used to distinguish the image fromthe pre-image. The image always has a prime after the letter such as A' .
It's always easier to understand a concept by looking at specific examples with pictures, so I suggest lookinag at the dilations examples below before trying to internalize the steps listed below that explain the general formula for dilating a point with coordinates of (2,4) by a scale factor of 1/2.
1) multiply both coordiantes by scale factor
(2 *½ ,4 *½)
2) Simplify
(1,2)
3) Graph(if required)
Demonstration of Dilation, Scale factor of 3
Practice Problems on Dilations
Perform a Dilation of 3 on point A (2,1) which you can see in the graph below.
Answer
Multiply the coordinates of the original point (2,1), called the image , by 3 .
Image's coordinates = (2 *3, 1*3 )
to get the coordinates of the image (6, 3)
Perform a Dilation of 4 on point A (2,3) which you can see in the picture below.
Answer
Multiply the coordinates of the original point (2,3), called the image , by 4 .
Image's coordinates = (2 *4, 3*4 )
to get the coordinates of the image (8, 12)
Perform a Dilation of ½ on point A (2, 4) which you can see in the picture below.
Graphing Calc
