1. Polygon Angles

2. Naming by # of sides. Polygons have specific names based on the number of sides they have: 3 – Triangle 4 – Quadrilateral 5 – Pentagon 6 – Hexagon 8 - Octagon 9 – Nonagon 10 – Decagon 12 – Dodecagon n – n-gon

3. Polygon Angle-Sum Theorem 4 sides 2 triangles 180° 6 sides 4 triangles 8 sides 6 triangles 360° total 720° total 1080° total

4. 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°