# Similar shapes

From Graphic maths

**Level: GCSE Maths**

Two shapes are *similar* if they are the same shape. They don't need to be the same size. These three shapes are similar:

All three shapes are similar, because they are the same shape.

## Similar polygons

Two polygons are similar if

- all their corresponding angles are equal.
- all their corresponding sides are proportional.

For example all regular hexagons are similar. If you take a regular hexagon and double the length of every side, it is still a regular hexagon because each side has changed by the same amount (shapes A and B below).

If you take a regular hexagon and just double just two sides, it is no longer similar, even though it still has the same angles (shape C).

## Triangles

For similar triangles there are special rules.

## Other shapes

Other shapes can be similar. For example, all circles are similar, even if they do not have the same radius.