2. 1 Geometry Section 4-1A Angles Inside the Triangle Pg. 242

3. 2 A repeating pattern of figures that completely covers a plan region without gaps or overlaps. We will soon investigate several geometric figures to see whether or not they can be used to tessellate a plane. Tessellation: Tessellations

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6. 5 Triangle: A figure formed by three segments that connect three noncollinear points. side vertex Label the parts of the triangle. Pg. 242 Triangles

7. 6 Scalene Triangle – no congruent sides. Isosceles Triangle – 2 congruent sides. Equilateral Triangle – All sides congruent. Pg. 243 Triangle Classification by Sides

8. 7 base leg base angle vertex angle Non-right triangles Right triangles leg hypotenuse Pg. 244 Triangles

9. 8 Try it: Two angles of a triangle measure 40 o and 58 o. What is the measure of the third angle? 180 – (40 + 58) = 82 o Try It: Pg. 244

10. 9 Triangle Classification by Angles: Acute Triangle – all angles acute. Obtuse Triangle – 1 obtuse angle. Equiangular Triangle – All angles congruent. Pg. 244

11. 10 Triangle Angle-Sum Theorem: The sum of the measures of the angles of a triangle is 180 o. http://mathopenref.com/triangleinternalangles.html Triangle Angle-sum Theorem

12. 11 Name and classify each triangle, using both angle and side classification. #1, 2 Pg. 245 J L M N O P Isosceles Scalene  JLM  NOP RightObtuse Exercises

13. 12 #3,4 Pg. 245 Name and classify each triangle, using both angle and side classification. PQ R 4.33.6 5.0 T S U Equilateral  PQR Scalene  STU EquiangularAcute Exercises

14. 13 #6 Pg. 245 Is it possible for each type of triangle to exist? If so, sketch it. If not, explain why. Obtuse Isosceles Exercises

15. 14 #7 Pg. 245 Is it possible for each type of triangle to exist? If so, sketch it. If not, explain why. Right Equilateral Exercises Not possible. In an equilateral triangle, every angle is 60 o.

16. 15 #8 Pg. 245 Is it possible for each type of triangle to exist? If so, sketch it. If not, explain why. Right Scalene Exercises

17. 16 FP is one side of a triangle on the grid. List the possibilities for the third vertex if the triangle is a: #9 Pg. 246 a. obtuse b. right c. isosceles d. Suppose the third vertex of the triangle is chosen randomly from the points shown in red. What is the probability that the triangle will be a right triangle? Exercises B, C, D, E, V, W, X, Y G, H, I, J, L, Q, R, S, T H, L, M, N, O, R 3434

18. 17 #11, 12 Pg. 246 Find the measure of angle 1. 1 40 o 72 o 1 57 o 180 – (40 + 72) = 68 o 180 – (90 + 57) = 33 o Exercises

19. 18 Find the measure of angle 1. #13, 14 Pg. 246 41 o 81 o 1 1 50 o  a and  b are corresponding  ’s and are . 180 – (81 + 41) = 58 o a b 41 o  a must = 40 o. a  a +  b = 90 o therefore,  b = 50 o and  c = 50 o 50 o 180 – (50 + 50) = 80 o Exercises

20. 19 Homework: Practice 4-1A #1-3 – You cannot “name” them. Mistake on worksheet.