 # KIDS Rules What are the KEY words What

• Slides: 31  KIDS Rules What are the KEY words? What is the INSTRUCTION? Do you need a DIAGRAM? Have you made your SOLUTION clear? Angles • Exam style question • Angles in parallel lines • Angles around a point • Angles in triangles/ quadrilaterals • Angle definitions Can you match the angle types with their correct definitions? Exactly 90 degrees Obtuse Angle Smaller than 90 degrees Reflex Angle Between 90 and 180 degrees Right Angle Bigger than 180 degrees Acute Angle Reflex Acute Right Angle. Obtuse 1. Angles on a straight line add up to 2. Angles around a point add up to 3. Angles in a triangle add up to Isosceles Triangle • 2 Angles equal Scalene Triangle • All Angles unequal b a Right-Angled Triangle  Answers 110 o 48 o 75 o External angles in polygons External angles always add up to 360 o So for a REGULAR polygon, each external angles will be… Interior angles in polygons We already know that external angles always add up to 360 o So for a REGULAR polygon, each INTERNAL angles will be… Your turn 1. Calculate the exterior angle for a 9 sided shape 2. Calculate the interior angle for a 12 sided shape 3. A regular shape has interior angle of 135 o, How many sides does it have? Answers 1. Calculate the exterior angle for a 9 sided shape 360/9= 40 o 2. Calculate the interior angle for a 12 sided shape EXT 360/12= 30 INT 180 -30= 150 o 3. A regular shape has interior angle of 135 o, How many sides does it have? First calculate the EXTERIOR; 180 -135= 45 360/45= 8 So an 8 sided shape Now try section A from your workbook Angles on parallel lines Alternate angles (Z) 84 o 28 Angles on parallel lines Corresponding angles (F) 29 o 132 o Angles on parallel lines o Co-interior angles (C) – Total 180 127 o 57 o These require more than one angle fact 147 o 57 o Find the missing angles- Your turn 1 2 3 45 x x 5 4 x 40 105 50 6 x 115 y x x y 83 y Find the missing angles- Answers 1 2 45 40 x 45 x 40 5 4 3 105 x 50 50 x 83 6 115 x 105 115 y x 115 105 y 83 y 180 -83= 97  Exam style question- Answer (a) Find angle x. Give reasons for your answer Shape ABCD is a quadrilateral. Angles must add up to 360. So the first missing angle at A is 132. Angles on a straight line add up to 180 so 180 -132= 48 so angle x=48 o (b) Find angle y. Give reasons for your answer (2 marks). Alternate angles are equal so angle y=64 o Now try section B from your workbook Exam style questions Find the size of the angle marked x A B C Exam style questions 108 60 360 - (108+60)= 84 Exam style questions 58 o 58 Because alternate angles are equal Exam style question- Your turn BEG and CFG are straight lines. ABC is parallel to DEF. Angle ABE = 48°. Angle BCF = 30°. (a) (i) Write down the size of the angle marked x. x =. . . . . ° (ii) Give a reason for your answer. . . . . . . (b) (i) (2) Write down the size of the angle marked y. y =. . . . . ° (ii) Give a reason for your answer. . . . . . . (2) (Total 4 marks) Exam style question- Answers BEG and CFG are straight lines. ABC is parallel to DEF. Angle ABE = 48°. Angle BCF = 30°. (a) (i) Write down the size of the angle marked x. x =. . . . 48. . ° (ii) Give a reason for your answer. . . . Alternate angle are equal, the angle at B is alternate because of the parallel lines. . . (b) (i) (2) Write down the size of the angle marked y. y =. . . . 30. . ° (ii) Give a reason for your answer. Corresponding with the angle at C (2) (Total 4 marks) Now try section C from your workbook