is a point given by a center point O
and a scale factor r
The of each point is on the starting at the center and going through the . The distance of the image from the center is calculated as follows.
In this formula O
is the center of the dilation, r
is the scale factor, A
is the preimage, and
is the image point. This is illustrated on the diagram. Move point A
and see how the image point moves.
When the scale factor is greater than 1,
the dilation is called an enlargement
. When the scale factor is between 0
the dilation is called a reduction