2 Learning Outcomes Find missing interior angles in a polygon Find missing exterior angles in a polygonFind missing interior angles in a regular polygonFind missing exterior angles in a regular polygonTessellate shapes
3 Polygons All shapes with straight sides 3-sided Triangle 4-sided Quadrilateral5-sided Pentagon6-sided Hexagon7-sided Heptagon8-sided Octagon9-sided Nonagon10-sided Decagon
4 Interior AnglesRemember a triangle adds to 180o!
5 Sum of Interior Angles Sum of Interior Angles = Number of Triangles × 180Sum of Interior Angles = (n – 2)× where n = number of sides
6 Exterior AnglesRemember a straight line adds to 180o!
7 Sum of Exterior AnglesSum of ALL exterior angles = 360o
8 Regular Polygons Regular polygon has equal sides and equal angles 1 exterior angle = 360 ÷ number of sides1 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 24oCalculate the number of sides in a polygon if its interior angle is 171o