2. Warm up OBJECTIVE: Students will classify triangles by there sides and angles and find missing angle measurements in triangles right acute obtuse When lines are parallel as indicated, the alt. int.  ’s 

3. OBJECTIVE: Students will analyze and classify Triangles by sides & angles, prove triangles congruent & use coordinate geometry to investigate triangle relationships. Why? Triangles are used to add strength to structures in real-world situations. For example, the frame of a hang glider involves several triangles. Mastery is 80% or better on Practice Problems and 5- Minute Checks.

4. Copy those terms for which you are unfamiliar

5. (3 ways) 023 Skill Development

6. Think….Ink…Share….Quick Write In your own words compare and contrast isosceles, scalene and equilateral triangles. Hint: How are they similar? Different?

7. (4 ways) 1313 equiangular  ’s are also equilateral Skill Development

8. isosceles acute isosceles 72,72,36

9. Pair Share With a partner discuss the criterion in the following triangles: Acute Right Obtuse Equiangular

10. x x

11.  RST is a right  (3--1) (-3-3) (3-5) (-3-5) (3-2) (-1-2) right 6 -4 8 2 3 2 3 2 3 - Skill Development

12. Two of the most important theorems you ever need

13. What should we do now? 3x – 9 = x + 73 2x = 82 x = 41 Guided

14. 2x + x + 90 = 180  sum theorem 3x = 90 x = 30 What kind of triangle is this? Right scalene Guided ……White Boards

15. Homework Day 1 of 2 Page 221 #1-15 all

16. Recall: 8x x (  sum corollary)

17. How’s this for a challenge? Hint: draw and label a picture ABC Which angle is biggest? Let x = the smallest angle x 2x 3x x + 2x + 3x = 180  sum theorem 6x = 180 x = 30 m  A = 2(30) = 60 m  B = 30 m  C = 3(30) = 90

18. Don’t be afraid to recognize properties we used last week Notice the parallel lines Y = 30 alt int  ’s  x = 60 corollary to  sum OR x + 30 = 90 ext  theorem x = 60

19. Find y first y = 90 – 39 = 51 Find this  ? = 180 – (50+51) = 79 x + 56 + 79 = 180  sum Theorem x = 45 corollary to  sum

20. Sometimes it “helps” to “separate” the triangles. Label our known values xx 25  20  yy yy 25  Find y y+25 = 90 y = 65 By ∆ sum, this angle is 95  So x = 180 - 95= 85

21. Exit Slips 1.How many ways can a triangle be classified by its sides? Name them. 2.How many ways can a triangle by classified by its angles? Name them. 3.What do all the angles of any triangle ALWAYS add up to? Name the theorem. 4.Find x and y. (copy picture)

22. WHAT WAS TODAYS OBJECTIVE ?? STUDENTS WILL ANALYZE TRIANGLES, FIND THEIR MEASURES AND CLASSIFY THEM BY THEIR SIDES AND THEIR ANGLES.

23. Home Work Pages 221-222 #16-37 all