Similar Polygons

Two polygons are similar (~) if:

1. All corresponding angles are congruent.
2. All corresponding sides are proportional.

Scale Factor

The scale factor is the ratio of corresponding side lengths. If △ABC ~ △DEF with scale factor k, then AB/DE = BC/EF = AC/DF = k.

Properties of Similar Polygons

• Corresponding angles are congruent.
• Corresponding sides are proportional.
• Ratio of perimeters = scale factor k.
• Ratio of areas = k².

Example: If two similar rectangles have a scale factor of 3:5, and the smaller has perimeter 24, the larger has perimeter 24 × (5/3) = 40.