Definitions

Lesson 1: Similar Polygons - Definitions

   Constructing Knowledge

You have explored similar triangles and you likely noticed that in similar triangles, the angle measures are the same but the side lengths are not. Congruent triangles are exact replicas of each other, meaning the side lengths and angle measures are the same.

Similar Triangles Triangles that have the same shape, with the same three angle measures

Congruent Triangles Triangles that are identical in size and shape. All three angle measures and all three side lengths are the same.

Triangles are not the only shapes that can be similar and congruent. Polygons can also be similar.

For this chapter, it will be important to understand the definitions:

polygon: a closed shape with a minimum of three straight sides.

corresponding sides: sides that occupy the same relative position in similar polygons

corresponding angle: congruent angles that occupy the same relative position in similar polygons

corresponding side length ratio: the ratio between the lengths of corresponding sides of two polygons

scale factor: the enlargement or reduction factor between two polygons

similar polygons: polygons whose corresponding side length ratios and corresponding angle measures are equal. They are the same shape. However, they may be different sizes.

congruent polygons: polygons whose corresponding side lengths and corresponding angle measures are equal. They are identical.

Symbols

A' - the ' is another way to name a side. The ' symbol is read as "prime". You would pronounce A' as "A prime".

~ - this symbols means "is similar to".

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