2. Transparency 2 Click the mouse button or press the Space Bar to display the answers.

3. Splash Screen

4. Example 2-3b Objective Find missing angle measures in triangles and classify triangles by their angles and sides

5. Example 2-3b Vocabulary Triangle A figure formed by three line segments that intersect only at their endpoints

6. Example 2-3b Vocabulary Acute triangle A triangle having three acute angles

7. Example 2-3b Vocabulary Obtuse triangle A triangle having one obtuse angle

8. Example 2-3b Vocabulary Right triangle A triangle having one right angle

9. Example 2-3b Vocabulary Scalene triangle A triangle with no congruent sides

10. Example 2-3b Vocabulary Isosceles triangle A triangle that has at least two congruent sides

11. Example 2-3b Vocabulary Equilateral triangle A triangle that has three congruent sides

12. Lesson 2 Contents Example 1Find a Missing Angle Measure Example 2Classify Triangles Example 3Classify Triangles

13. Example 2-1a Find the value of x in The sum of the 3 angles of a triangle = 180 0 1/3 Write an equation Replace m  P with 17 17 Replace m  Q with 46 17 + 46 Define variable as m  r 17 + 46 + m  R Bring down = 180 17 + 46 + m  R = 180

14. Example 2-1a Find the value of x in Combine “like” terms 1/3 17 + 46 + m  R = 180 63 Ask “what is being done to the variable”? The variable is being added by 63 Do the inverse on both sides of the equal sign Bring down + m  R = 180 63 + m  R = 180

15. Example 2-1a Find the value of x in Bring down 63 1/3 17 + 46 + m  R = 180 63 63 + m  R = 180 63 Subtract 63 63 - 63 Bring down + m  R = 180 63 - 63 + m  R = 180 Subtract 63 63 - 63 + m  R = 180 - 63 Combine “like” terms 0 Bring down + m  R = 0 + m  R = Combine “like” terms 0 + m  R = 117

16. Example 2-1a Find the value of x in Use the Identity Property to add 0 + m  R 1/3 17 + 46 + m  R = 180 63 63 + m  R = 180 6363 - 63 63 - 63 + m  R = 18063 - 63 + m  R = 180 - 63 0 0 + m  R =0 + m  R = 117 m  R = 117 Add dimensional analysis m  R = 117 0 Answer:

17. Example 2-1b Answer: m  I = 35 0 Find the value of x in 1/3

18. Example 2-2a Classify the triangle by its angles and its sides. Answer: right, isosceles triangle 2/3  B is a right angle Angles Right triangle Sides Segments AB and BC are congruent Isosceles triangle

19. Example 2-2b Classify the triangle by its angles and its sides. Answer: acute, equilateral triangle 2/3

20. Example 2-3a Classify the triangle by its angles and its sides. Answer: Obtuse, scalene triangle 3/3  Q is an obtuse angle Angles Obtuse triangle No sides are congruent Sides Scalene triangle

21. Example 2-3b Classify the triangle by its angles and its sides. Answer: right, scalene triangle * 3/3

22. End of Lesson 2 Assignment Lesson 6:2Triangles and Angles3 - 23 All