1. 27-Oct-15Created by Mr. Lafferty Revision of Level E Interior / Exterior Angles Angle Properties www.mathsrevision.com Angles in Time

2. 27-Oct-15Created by Mr. Lafferty 120 o 95 o Angle Properties www.mathsrevision.com Angles round a point Add up to 360 o 115 o Two angles making a straight line add to 180 o angles opposite each other at a cross are equal. 34 o 3 angles in a triangle ALWAYS add up to 180 o. 50 o 40 o 65 o 90 o 146 o 146 o 145 o Revision of Level E

3. 27-Oct-15Created by Mr. Lafferty Angle Properties www.mathsrevision.com Two angles in a isosceles Are equal ALL angles in an equilateral triangle are 60 o d = 115 o aoao coco bobo gogo fofo hoho eoeo is corresponding to d and must be 115 o is opposite to d and must be 115 o is must be 65 o (straight line) is alternate to c and must also be 65 o h b c e Revision of Level E

4. 27-Oct-15Created by Mr. Lafferty www.mathsrevision.com Polygons A polygon is a “many-sided closed straight-lined figure” This 5-sided (polygon) is called a PENTAGON Irregular Pentagon Interior and Exterior Angles

5. 27-Oct-15Created by Mr. Lafferty www.mathsrevision.com Polygons A polygon is a “many-sided closed straight-lined figure” PentagonHexagonOctagon If all the sides and angles are the same it is called REGULAR POLYGON. We will only be dealing with regular polygons in this section. Interior and Exterior Angles

6. 27-Oct-15Created by Mr. Lafferty www.mathsrevision.com Polygons Some useful points about regular polygons : All the triangles around the centre are isosceles. Pentagon 72 o Hexagon 60 o Octagon 45 o Interior Angles Interior Angle Angle at the centre is 360 o To find one angle at the centre, take 360 o and divide it by how many triangles you have Interior and Exterior Angles

7. 27-Oct-15Created by Mr. Lafferty www.mathsrevision.com Level F - Polygons Worksheet Ex2 Decagon (10 sided) Heptagon (7 sided)Hexagon (6 sided)Pentagon (5 sided) Octagon (8 sided)Nonagon (9 sided)

8. 27-Oct-15Created by Mr. Lafferty www.mathsrevision.com Polygons What you should have found : Interior angle = 180 – (360 ÷ n) n = Number of sides eg. A hexagonal has interior angle is: Interior angle = 180 – (360 ÷6 ) = 120 o Interior and Exterior Angles

9. 27-Oct-15Created by Mr. Lafferty www.mathsrevision.com Polygons eg. For the pentagon above : Exterior angle = 180 – interior angle Pentagon This is called the “Exterior angle” B A E CD O Q Exterior angle = 180 – 108 = 72 o Interior and Exterior Angles