MTH 3-17a 16-May-15Created by Mr. Lafferty Revision of Level E Interior / Exterior Angles Angle Properties Angles in Time

MTH 3-17a 16-May-15Created by Mr. Lafferty Starter Questions 5 cm 3 cm 10 cm 3 cm

MTH 3-17a 16-May-15Created by Mr. Lafferty Learning Intention Success Criteria 1.Remember basic properties for angles. 1.We are reviewing angle properties. 2.Apply properties to solve angle problems.. Angle Properties Revision of Level E

16-May-15Created by Mr. Lafferty 120 o 95 o Angle Properties 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 MTH 3-17a

16-May-15Created by Mr. Lafferty Angle Properties 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 MTH 3-17a

16-May-15Created by Mr. Lafferty Now try Exercise 1 Ch3 (page 21) Copy out shapes Angle Properties Revision of Level E

MTH 3-17a 16-May-15Created by Mr. Lafferty Starter Questions 7 cm 5 cm 20 cm 3 cm

MTH 3-17a 16-May-15Created by Mr. Lafferty Learning Intention Success Criteria 1.To know the term polygon. 1.We are exploring interior and exterior angles of a polygon. 2.Understand steps for calculating the interior and exterior angle of a polygon. Polygons Interior and Exterior Angles

MTH 3-17a 16-May-15Created by Mr. Lafferty 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

MTH 3-17a 16-May-15Created by Mr. Lafferty 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

MTH 3-17a 16-May-15Created by Mr. Lafferty 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

16-May-15Created by Mr. Lafferty Level F - Polygons Worksheet Ex2 Decagon (10 sided) Heptagon (7 sided)Hexagon (6 sided)Pentagon (5 sided) Octagon (8 sided)Nonagon (9 sided) MTH 3-17a

16-May-15Created by Mr. Lafferty Now try Exercise 2 Ch3 (page 23) Q1-Q6 Use worksheet Provide Polygons Interior and Exterior Angles MTH 3-17a

16-May-15Created by Mr. Lafferty 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

MTH 3-17a 16-May-15Created by Mr. Lafferty 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

16-May-15Created by Mr. Lafferty Now try Exercise 2 Ch3 (page 23) Q8-Q9 Use worksheet Provide Polygons Interior and Exterior Angles MTH 3-17a

16-May-15Created by Mr. Lafferty Starter Questions 10 cm 3 cm 7 cm 4 cm

16-May-15Created by Mr. Lafferty Practice on Angles Now try Exercise 3 Ch3 (page 26) Polygons Interior and Exterior Angles MTH 3-17a