Interior Angles of Polygons n 2 Find the

Interior Angles of Polygons (n – 2) Find the triangles connection between the number o (n –and 2)180 of=sides the number of triangles. 180 o 4 sides Quadrilateral 5 sides 2 2 x 180 o = 360 o 3 180 o 6 sides 4 180 o The sum of the interior angles of 180 o and” n” sided polygon is? Hexagon 4 x 180 o = 720 o 7 sides 5 180 o Pentagon 3 x 180 o = 540 o 180 o Heptagon/Septagon 5 x 180 o = 900 o

Interior Angles of Polygons Calculate the angle sum and interior angle of each of these regular polygons. 2 1 3 7 sides 9 sides 4 10 sides to 1 dp 11 sides to 1 dp Septagon/Heptagon Nonagon Decagon Hendecagon 900 o/128. 6 o 1260 o/140 o 1440 o /144 o 1620 o /147. 3 o 6 5 7 12 sides 16 sides 20 sides Dodecagon Hexadecagon Icosagon 1800 o /150 o 2520 o /157. 75 o 3240 o /162 o

Interior Angles of Polygons Find the unknown angles below. w 100 o 95 o 110 o 3 x 180 o = 540 o 2 x 180 o = 360 o 360 – 245 = 115 o 125 o 100 o 121 o 117 o 75 o 70 o 140 o Diagrams not drawn accurately. x y 4 x 180 o = 720 o 720 – 603 = 117 o 540 – 395 = 145 o 125 o 138 o z 105 o 138 o 133 o 137 o 5 x 180 o = 900 o 900 – 776 = 124 o

Interior Angles of Polygons Now try these ones yourself. 1 115 o 120 o y 120 o 115 o 2 95 o 85 o 155 o 4 x 180 o = 720 o 720 – 595 = 125 o 3 x w 75 o 2 x 180 o = 360 o 360 – 240 = 120 o 3 x 180 o = 540 o Diagrams not drawn accurately. 4 88 o 540 – 418 = 122 o 125 o 165 o 150 o 95 o 155 o z 5 x 180 o = 900 o 900 – 780 = 120 o

Interior Angles of Polygons

Interior Angles of Polygons Calculate the angle sum and interior angle of each of these regular polygons. 2 1 3 7 sides 9 sides 4 10 sides 11 sides to 1 dp Septagon/Heptagon Nonagon 6 5 Decagon Hendecagon 7 12 sides 16 sides 20 sides Dodecagon Hexadecagon Icosagon

Interior Angles of Polygons Find the unknown angles below. w 70 o 140 o 100 o 75 o 95 o 110 o 75 o 125 o 100 o 121 o 117 o Diagrams not drawn accurately. x y 125 o 138 o 133 o 115 o z 105 o 137 o

Interior Angles of Polygons Now try these ones yourself. 1 115 o 120 o y 120 o 2 155 o x 75 o 120 o Diagrams not drawn accurately. 4 w 88 o 95 o 85 o 3 75 o 115 o 125 o 165 o 150 o 95 o 155 o z