Polygons: (polygon means "many angles")

Polygons are made by coplanar segments such that:

1. Each segment exactly intersects two other segments, one at each
endpoint.

2. No two segments with a common endpoint are collinear.

convex polygon is a polygon that has no side in the interior of the polygon.

ex.

Polygons are named according to the number of sides they have. The triangle is simplest polygon. The terms that apply to triangles can also be applied to polygons.

A diagonal of a polygon is a segment that joins two non consecutive vertices.

The red dotted lines represent the diagonals of the polygon.

If the diagonals of a polygon is drawn from one vertex, then the sum of the measures of the angles of the polygon can be calculated.

Theorem:
The sum of the measured angles of an n sided polygon is (n-2)180.

ex.

number of sides = 5
(n - 2)180 = (5 - 2)180
(3)180 = 640°


Theorem:
The sum of the measures of the exterior angles of a convex polygon
is an angle at each vertex is 360.

A regular polygon is a polygon that is both equilateral and equiangular.