1. Homework, red pen, pencil, highlighter, ruler, GP NB
U3D8
Homework, red pen, pencil, highlighter, ruler, GP NB
Have Out:
Bellwork:
Graph the inequality: +1
Dividing line: +1 y x 1 2 3 4 5 -1 -2 -3 -4 -5
Test point (0, 0) +2
False
y-int: (0,1) +1 +1 +1 +1
for labeling axes & scale

2. Send one member of your team to pick up:
PS-92
Angles and Triangles
About a half page down, draw a horizontal line using a ruler. Place a point in the middle of your line and label it A. A
Send one member of your team to pick up:
Triangle worksheet (ONE per group)
Scissors (TWO per group)

3. Number the corners of your triangle with 1, 2, and 3.
PS-92
Angles and Triangles
Your team has been given 4 different triangles. Notice that every triangle has a different shape. 1 3 2
Each team member will have their own triangle. Highlight each of the edges of your triangle.
Number the corners of your triangle with 1, 2, and 3.

4. PS-92 1 3 2
3.Separate off each corner of the triangle in LARGE PIECES by tearing along a jagged edge.

5. PS-92 1 3 2
3.Separate off each corner of the triangle in LARGE PIECES by tearing along a jagged edge.
4.Place the 3 resulting angles so that they are adjacent angles on the UPPER side of the line in your notebook with all 3 vertices at the labeled point A.
Tape the corners together at point A.
Be sure that the angles do not overlap. A

6. Write a conjecture about the sum of the 3 angles of any triangle.
PS-92
5.Compare your results with your team. What do you notice?
Write a conjecture about the sum of the 3 angles of any triangle.
The sum of the 3 angles of any triangle is 180°. 2 1 3 A

7. >> If m1=m4 and m3=m5 and then by substitution
PS-93
Justify your answers for the following. A)
They are adjacent angles that form a straight angle.
>> 1 2 3 B 4 A 5 C B)
|| Alternate interior s are equal. C)
|| Alternate interior s are equal.
D) How can you put the equations from parts (A), (B), and (C) together to form an equation that represents the sum of the interior angles of a triangle?
If m1=m4 and m3=m5 and
then by substitution
m4 + m2 + m5 = 180.

8. The sum of the measures of the interior angles of a triangle is 180°.
PS-93
Add to your notes:
This process proves the conjecture, and a proven conjecture is known as a theorem.
Triangle Interior Angle Sum Theorem
( sum thm)
The sum of the measures of the interior angles of a triangle is 180°.
The TRIANGLE INTERIOR ANGLE SUM THEOREM is a theorem because doing parts (A) – (D) produced a sequence of true, connected facts that verify the final statement.

9. PS-96
Find the measures of the missing angles by using the theorem about the sum of the measures of the angles of a triangle. x A) B) C)
80°
90°
60° x x x x x D) E) F)
70°
62°
20°
50° x x
120° x

10. 90° + 60° + x = 180° 80° + x + x = 180° x + x + x = 180° ( sum thm)
PS-96
Find the measures of the missing angles by using the theorem about the sum of the measures of the angles of a triangle. x A) B) C)
80° x
90°
60° x
90° + 60° + x = 180°
80° + x + x = 180°
x + x + x = 180°
( sum thm)
( sum thm)
( sum thm)
150° + x = 180°
80° + 2x = 180°
3x = 180°
-150° °
-80° ° 3 3
x = 30°
2x = 100°
x = 60° 2 2
x = 50°

11. 62° + 50° + x = 180° y + 120° = 180° 20° + 90° + x = 180° -120° -120°
PS-96
Find the measures of the missing angles by using the theorem about the sum of the measures of the angles of a triangle. D) E) F)
120°
70° x
50°
62° x
20° x y
(Linear pair)
62° + 50° + x = 180°
y + 120° = 180°
20° + 90° + x = 180°
-120° °
( sum thm)
( sum thm)
y = 60°
112° + x = 180°
110° + x = 180°
-112° °
70° + y + x = 180°
-110° °
( sum thm)
x = 68°
x = 70°
70° + 60° + x = 180°
130° + x = 180°
-130° °
x = 50°

12. Finish the rest of the assignment...
Work on PS then
Finish the rest of the assignment... PS
Quiz Thursday!