POLYGONS

Yes, it’s another Greek word. ‘Poly’ meaning multiple or more than 2 in this case, and ‘gon’ meaning angle. So a polygon is a geometric 2-dimensional figure made up of 3 or more line segments, called sides, and has 3 or more angles.

There are 2 more requirements for a polygon:

· The sides of a polygon are connected end to end and make a closed path.

· The sides of a polygon do not cross (intersect).

Here are some samples of polygons:

These are not polygons:

Curved line is not a line segment.	The sides must form a closed path.
A polygon must have at least 3 sides.	The sides of a polygon must not cross.

Convex polygons – is a polygon in which all the sides are pushed outward.

Triangle

Quadralateral

Pentagon

Hexagon

Nonconvex (concave) polygons have at least two sides pushed in.

Quadralateral

Hexagon

Pentagon

Octagon

A polygon is a regular polygon if:

· The sides are all the same length

· The angles are all the same size.

Equilateral triangle

Square

Octagon

Similar and Congruent Polygons:

Two polygons are similar if they have the same shape, but not necessarily the same size.

Two polygons are congruent if they have both the same shape and the same size.

These are polygons similar: (same shape; different size)

These are not: (different shape)

These polygons are congruent: (same shape; same size)

These are not: (same shape; different size)