Good Afternoon!

1. Good Afternoon! Today we will be learning about Triangles (isosceles, equilateral, right) Let’s warm up : Find the missing angle around a point: 1) 40° + 110° + a° + 40° = 360° 1) 170 ° 2) 35° + 95° + b° + 70° = 360° 2) 160 ° 3) 55 ° 3) What is the Complement of 35° ? 4) What is the Supplement of 66° ? 4) 114 ° CONFIDENTIAL

2. Let’s review what we did in the last session What Is an Angle? An angle is a combination of two rays with a common endpoint. B angle AOB vertex O A arm The endpoint (O) is known as the vertex of the angle And the rays (OA and OB) are called the sidesor arms of the angle . CONFIDENTIAL

3. Review Measuring angles in Degrees We often measure degrees using a protractor. The normal protractor measures 0° to 180°. CONFIDENTIAL

4. Review Angles On a Straight Line If we know one angle is 45°, what is angle “x" ? x 45° Angle x will be 180° − 45° = 135° This method can be used to find angles on one side of a straight line. CONFIDENTIAL

5. Review Angles Around a Point Angles around a point will always add up to 360 degrees. 110° 40° 60° 150° The angles here all add to 360°. 40° + 110° + 150° + 60° = 360° Because of this, if there is an unknown angle we can always find it. CONFIDENTIAL

6. Review Complementary Angles Two Angles are Complementary if they add up to 90 degrees (a Right Angle). 60° 30° These two angles (40° and 50°) are Complementary Angles, because they add up to 90°. But the angles don't have to be together to Complement each other. CONFIDENTIAL

7. Review Supplementary Angles Two Angles are Supplementary if they add up to 180 degrees(a StraightAngle). 120° 60° These two angles (120° and 60°) are Supplementary Angles, because they add up to 180°. But the angles don't have to be together to Supplement each other. CONFIDENTIAL

8. Let’s start with Triangles (isosceles, equilateral, right) A polygon is a plane (2-dimensional ) shape. Polygon is made of straight lines, and the shape is "closed" . Example: Triangle, Quadrilateral, Pentagon. Pentagon Triangle Quadrilateral CONFIDENTIAL

9. A a B c C b Today we will learn about triangles. A triangle is one of the basic shapes of geometry: A polygon with three corners or vertices and three sides or edges which are line segments. angle ACB Or angle c vertex arm The three angles always add to 180°. CONFIDENTIAL

10. Interior Angle: An Interior Angle is an angle inside a shape. Exterior Angle: The Exterior Angle is the angle between any side of a shape, and a line extended from the next side. Exterior Angle 135° Interior Angle 45° If you add up the Interior Angle and Exterior Angleyou get a straight line, 180°. CONFIDENTIAL

11. A a B b c C Triangle Classification The basic elements of any triangle are its sides and vertices. Triangles are classified depending on relative sizes of their elements. Triangles can be classified according to their internal angles. Acute Triangle: An acute triangle is a triangle whose angles are all acute (i.e. less than 90°). In the acute triangle shown above, a, b and c are all acute angles. CONFIDENTIAL

12. a° 90° b° Right Triangle: A right triangle is a triangle with a right angle (i.e. 90°). The side opposite the right angle is always the triangle's longest side. It is called the hypotenuse of the triangle. The other two sides are called the legs. hypotenuse leg right angle leg CONFIDENTIAL

13. a° >90° b° Obtuse Triangle: An obtuse triangle has one obtuse angle (i.e. greater than 90º). The longest side is always opposite the obtuse angle. In the obtuse triangle shown above, a is the obtuse angle. CONFIDENTIAL

14. a a 60º 60º 60º a Types of Triangles There are three special names given to triangles that tell how many sides (or angles) are equal. The triangle classification is summarized as follows: Equilateral Triangle:An equilateral triangle has all three sides equal in length. Its three angles are also equal and they are each 60º. CONFIDENTIAL

15. a a xº xº b xº zº a c yº Isosceles Triangle:An isosceles triangle has two sides of equal length. The angles opposite the equal sides are also equal. Scalene Triangle:A scalene triangle has no sides of equal length. Its angles are also all different in size. CONFIDENTIAL

16. Combining the Names There are two types of right angled triangle: Remember the little square in the triangle tells us that it is a right angled triangle. CONFIDENTIAL

17. A triangle has angles 46º, 63º and 71º. What type of triangle is this? Since all its angles are less than 90°, it is an acute triangle. CONFIDENTIAL

18. BREAK CONFIDENTIAL

19. GAME Click on the link below for some exciting puzzle http://www.thekidzpage.com/onlinejigsawpuzzles/jigsaw-puzzles/12-piece-jigsaw/03-04-06-jewels.html CONFIDENTIAL

20. 7 cm 4 cm 4 cm 5cm 3 cm 2cm 2cm 2cm Assignments Classify each triangle as Equilateral, Isosceles or Scalene : 1) 2) 1) Equilateral triangle 2) Isosceles triangle 3) 3) Scalene triangle CONFIDENTIAL

21. 30º 60º 90º 60º 60º 60º Classify each triangle as Acute, Right or Obtuse : 4) 5) 5) Right triangle 95 º 4) Obtuse triangle 6) 6) Acute triangle CONFIDENTIAL

22. Angles of the triangle are given. What type of triangles are the following? 7) 56º, 50º and 74º. 10) 60º, 60º and 60º. 7) Acute triangle 10) Equilateral triangle 11) 45º, 90º and 45º. 8) 105º, 48º and 27º. 8) Obtuse triangle 11) Right Isosceles triangle 9) 35º, 90º and 55º. 12) 36º, 64º and 90º. 9) Right triangle 12) Right Scalene triangle CONFIDENTIAL

23. A a B c C b Very Good! Let's Review Today we learnt about triangles. A triangle is one of the basic shapes of geometry: A polygon with three corners or vertices and three sides or edges which are line segments. angle ACB Or angle c vertex arm The three angles always add to 180°. CONFIDENTIAL

24. Review Interior Angle: An Interior Angle is an angle inside a shape. Exterior Angle: The Exterior Angle is the angle between any side of a shape, and a line extended from the next side. Exterior Angle 135° Interior Angle 45° If you add up the Interior Angle and Exterior Angleyou get a straight line, 180°. CONFIDENTIAL

25. A a B b c C Review Triangle Classification The basic elements of any triangle are its sides and vertices. Triangles are classified depending on relative sizes of their elements. Triangles can be classified according to their internal angles. Acute Triangle: An acute triangle is a triangle whose angles are all acute (i.e. less than 90°). In the acute triangle shown above, a, b and c are all acute angles. CONFIDENTIAL

26. a° 90° b° Review Right Triangle: A right triangle is a triangle with a right angle (i.e. 90°). The side opposite the right angle is always the triangle's longest side. It is called the hypotenuse of the triangle. The other two sides are called the legs. hypotenuse leg right angle leg CONFIDENTIAL

27. a° >90° b° Review Obtuse Triangle: An obtuse triangle has one obtuse angle (i.e. greater than 90º). The longest side is always opposite the obtuse angle. In the obtuse triangle shown above, a is the obtuse angle. CONFIDENTIAL

28. a a 60º 60º 60º a Review Types of Triangles There are three special names given to triangles that tell how many sides (or angles) are equal. The triangle classification is summarized as follows: Equilateral Triangle:An equilateral triangle has all three sides equal in length. Its three angles are also equal and they are each 60º. CONFIDENTIAL

29. a a xº xº b xº zº a c yº Review Isosceles Triangle:An isosceles triangle has two sides of equal length. The angles opposite the equal sides are also equal. Scalene Triangle:A scalene triangle has no sides of equal length. Its angles are also all different in size. CONFIDENTIAL

30. Review Combining the Names There are two types of right angled triangle: Remember the little square in the triangle tells us that it is a right angled triangle. CONFIDENTIAL

31. You have done a nice job. See you in the next session. CONFIDENTIAL