Polygon Angles

Naming by # of sides.

Polygons have specific names based on the number of sides they have:

3 – Triangle4 – Quadrilateral5 – Pentagon6 – Hexagon8 - Octagon

9 – Nonagon10 – Decagon12 – Dodecagonn – n-gon

Polygon Angle-Sum Theorem

4 sides

2 triangles

180°

180°180°

180°180°

180°

180°

180°

180°

180°

180°

180°

6 sides

4 triangles

8 sides

6 triangles

360° total720° total

1080° total

Polygon Angle-Sum Theorem

The sum of the measures of the angles of an n-gon is: (n – 2) x 180.

How many degrees in a 25-gon?

How many degrees in a pentagon?

(5 – 2) x 180 = 3 x 180 = 540°

(25 – 2) x 180 = 23 x 180 = 4140°