September 13, 2013 1) Sit. 2) Materials out. 3) Backpacks away. 4) Do Now SILENTLY.

1. September 13, 20131) Sit. 2) Materials out. 3) Backpacks away. 4) Do Now SILENTLY. Learning Goal: • IWBAT to determine whether two triangles are congruent by using the triangle congruence postulates and theorem. Homework: • HW 3.5: Triangle Congruence Worksheet ------------------------------------------------------------------- Do Now: Complete each congruence statement by naming the corresponding angle or side.

2. Agenda: • Do Now (15 min) • Exploring Triangle Congruence (20 min) • SSS and SAS Congruence (15 min) • Triangle Congruence Whiteboard (10 min) • ASA and AAS Congruence (10 min) • Triangle Congruence Whiteboard (10 min) • Closure (5 min) • Triangle Theorems Quiz (30 min)

3. Exploring SSS Congruence

4. Exploring SAS Congruence

5. Draw Conclusions • What did you notice about the triangles you made with the three straws? • What did you notice about the triangles you made with two straws and a 45° angle between them? • If you know that two sides of a triangle are congruent to two sides of another triangle, what other information do you need to tell whether the triangles are congruent?

6. Congruence Postulates

7. Congruence Postulates

8. Congruence Postulates • Decide whether enough information is given to prove that the triangles are congruent. If there is enough information, tell which congruence postulate you would use.

9. Triangle Congruence Activity • Teacher will project two triangles at a time on the board. • Your task is to determine whether it is possible to prove that the two triangles are congruent. If so, then state the congruence theorem you would use to prove it. • 1 min. independently journal, then 2 min. partner pair share per exercise. • Teacher will call on students to share and justify their responses.

10. Exercise #1 • Can you prove that the two triangles are congruent? Explain why or why not.

11. Exercise #2 • Can you prove that the two triangles are congruent? Explain why or why not.

12. Exercise #3 • Can you prove that the two triangles are congruent? Explain why or why not.

13. Exercise #4 • Can you prove that the two triangles are congruent? Explain why or why not.

14. Exercise #5 • Can you prove that the two triangles are congruent? Explain why or why not.

15. Exercise #6 • Can you prove that the two triangles are congruent? Explain why or why not.

16. Congruence Postulates

17. Congruence Postulates

18. Triangle Congruence Activity • Teacher will project two triangles at a time on the board. • Your task is to determine whether it is possible to prove that the two triangles are congruent. If so, then state the congruence theorem you would use to prove it. • 1 min. independently journal, then 2 min. partner pair share per exercise. • Teacher will call on students to share and justify their responses.

19. Exercise #1 • Can you prove that the two triangles are congruent? Explain why or why not.

20. Exercise #2 • Can you prove that the two triangles are congruent? Explain why or why not.

21. Exercise #3 • Can you prove that the two triangles are congruent? Explain why or why not.

22. Exercise #4 • Can you prove that the two triangles are congruent? Explain why or why not.

23. Exercise #5 • Can you prove that the two triangles are congruent? Explain why or why not.

24. Exercise #6 • Can you prove that the two triangles are congruent? Explain why or why not.

25. Other Congruence Postulates? • Angle-Angle-Angle (AAA) Congruence Postulate? http://www.mathopenref.com/congruentaaa.html • Side-Side-Angle (SSA) Congruence Postulate? http://www.mathopenref.com/congruentssa.html

26. Triangle Congruence Whiteboard Activity • Students work in pairs. Each pair receives a whiteboard, marker, and eraser. • Teacher will present practice exercises about the congruence of triangles on the board. • Your teams have 1 minute to solve the problem and write the answer on the whiteboard with its justification. • Display your whiteboard when the timer runs out.

27. Exercise #1 • State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.

28. Exercise #2 • State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.

29. Exercise #3 • State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.

30. Exercise #4 • State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.

31. Exercise #5 • State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.

32. Exercise #6 • State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.

33. Exercise #7 • State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.

34. Exercise #8 • State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.

35. Exercise #9 • State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.

36. Exercise #10 • State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.

37. Closure Take a moment to response to the following prompt in your notes. Please include a drawing along with an explanation. • If three angles of a triangle are the same as three angles of another triangle, are both triangles congruent? • The triangles are congruent because ____________________ . • The triangles are NOT congruent because _______________ .