Properties of enlargement

For an enlargement transformation of factor k, the image of an interval is k times the length of the original interval.

The image of an angle has the same size as the original angle.

The image of an interval is parallel to the original interval.

In the diagram below the image \(\triangle A^\prime B^\prime C^\prime\) is a scale drawing of the original figure \(\triangle ABC\), with ratio 1 : 2. In this illustration, the vertex \(A\) is used as the centre of enlargement.

Detailed description

Scale factors

For a scale factor k:

• If k > 1, then the image is larger than the original.
• If k < 1, then the image is smaller than the original.
• If k = 1, then no point moves and the image is the same as the original.