1. Interior and Exterior angles
Angles in a Polygon
Interior and Exterior angles

2. Interior and Exterior angles
Angles in a Polygon
Interior and Exterior angles
Aims
Know what the Exterior and Interior angles of a polygon are
Be able to find the Exterior and Interior angles
Be able to accurately draw a polygon

3. The pentagon

4. Interior Angle
Exterior Angle

5. How can you calculate the Interior and Exterior angles
Interior Angle
Exterior Angle
How can you calculate the Interior and Exterior angles
when all you know are the number of sides of this regular Pentagon?

6. Exterior angle = Middle angle = 360 ÷ 5 = 72o
Interior Angle
Exterior Angle
54o
72o
54o
108o
72o
54o
Middle angle =360 ÷ 5 = 72o
Interior angle = 180 – 72 = 108o
Exterior angle = Middle angle = 360 ÷ 5 = 72o

7. Your task is to find the size of the
Exterior and Interior angles of all these Polygons
Heptagon
Hexagon
Octagon
Decagon
Nonagon

8. Exterior and Interior angles of Polygons
Hexagon
Heptagon
Interior angle = 128.6o
Exterior angle = 51.4o
Interior angle = 120o
Exterior angle = 60o
Octagon
Nonagon
Interior angle = 135o
Exterior angle = 45o
Decagon
Interior angle = 140o
Exterior angle = 40o
Interior angle = 144o
Exterior angle = 36o