1. Chapter 24
Polygons

2. Learning Outcomes Find missing interior angles in a polygon
Find missing exterior angles in a polygon
Find missing interior angles in a regular polygon
Find missing exterior angles in a regular polygon
Tessellate shapes

3. Polygons All shapes with straight sides 3-sided Triangle
4-sided Quadrilateral
5-sided Pentagon
6-sided Hexagon
7-sided Heptagon
8-sided Octagon
9-sided Nonagon
10-sided Decagon

4. Interior Angles
Remember a triangle adds to 180o!

5. Sum of Interior Angles Sum of Interior Angles = Number of
Triangles × 180
Sum of Interior Angles = (n – 2)× where n = number of sides

6. Exterior Angles
Remember a straight line adds to 180o!

7. Sum of Exterior Angles
Sum of ALL exterior angles = 360o

8. Regular Polygons Regular polygon has equal sides and equal angles
1 exterior angle = 360 ÷ number of sides
1 interior angle = 180 – exterior angle

9. Examples Find the exterior and interior angle in a regular heptagon
Calculate the number of sides in a polygon if its exterior angle is 24o
Calculate the number of sides in a polygon if its interior angle is 171o

10. Tessellations
Tessellating means tiling