What is a Polygon?
Math definition:
A polygon is a closed figure formed by a finite number of coplanar segments such that:
1. The sides that have a common endpoint are noncollinear
2. each side intersects exactly two other sides, but only at their endpoints.
Simply Explained:
There are no openings in the figure
No sides overlap
The sides only meet at their endpoints
each side meets with two other sides.
In a convex polygon, all of the sides will point outward if they are extended. In a concave polygon, some of the sides will point inwards and have points inside of the figure.

Think of concave like a "cave" because it moves into the figure.
In a regular polygon, all of the sides are congruent and all of the angles are congruent.
Figure Name

Triangle

Quadrilateral

Pentagon

Hexagon

Heptagon

Octagon

Nonagon

decagon

11-gon

Dodecagon		 Sides

3

4

5

6

7

8

9

10

11

12
Sum of interior angles

180

360

540

720

900

1080

1160

1340

1520

1600
If n is the number of sides, and S is the sum of the angles, the formula to find the sum of the interior angles is S=180(n-2)

In a concave figure, the sum of the exterior angles (the angles formed by the extension of all of the segments in one direction) is 360.
Home
Hosted by www.Geocities.ws

1