Chapter 24 Polygons
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
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
Interior Angles Remember a triangle adds to 180o!
Sum of Interior Angles Sum of Interior Angles = Number of Triangles × 180 Sum of Interior Angles = (n – 2)× 180 where n = number of sides
Exterior Angles Remember a straight line adds to 180o!
Sum of Exterior Angles Sum of ALL exterior angles = 360o
Regular Polygons Regular polygon has equal sides and equal angles 1 exterior angle = 360 ÷ number of sides 1 interior angle = 180 – exterior angle
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
Tessellations Tessellating means tiling