A. A dilation takes a line not passing through the center of the dilation to a parallel line, and leaves a line passing through the center unchanged.

B. The dilation of a line segment is longer or shorter in the ratio given by the scale factor.

Common Core: HSG-SRT.A.1

Related Topics:

Common
Core (Geometry)

Common Core
for Mathematics

Dilations in Geometric Figures

This video explains the concept of dilating a geometric figure,
scale factor, and work through some basic examples involving
dilating figures.

In this lesson dilation and scale factor are defined. Then using examples we discuss positive and negative scale factor as well as scale factors that are greater than or less than one.

In this lesson we calculate scale factor and show dilation on a graph (coordinate plane).

Using a compass and straight edge to construct the dilation of a geometric shape.

This Demonstration allows you to explore some of the features of dilation , also called expansion or enlargement, in two dimensions. You can change the center of dilation. You can drag or add locators to change the shape of the object. You can also see the lines joining vertices to their images. This Demonstration is designed as a class activity, so by projecting the image on a whiteboard or an interactive board, students can demonstrate their skill by predicting the position of any hidden object.

Enlargement in Two Dimensions from the Wolfram
Demonstrations Project by Sergio Hannibal Mejia

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