1. Math CC7/8 – Sept. 15 Homework: p. 76 #1-5 Topic: Building Triangles
Things Needed Today (TNT):
Math Notebook/Pencil
Shapes & Designs 3.1
3.1 Assignment Worksheet/Bag of Poly Strips
Learning Log:
Topic: Building Triangles
Homework: p. 76 #1-5

2. What’s Happening?
Warm Up
Lesson- S&D 3.1!

3. Warm-Up End WRITE down each problem & SOLVE
1 minute
WRITE down each problem & SOLVE
Show ALL your work & THINKING
End

4. Check your work in a different colored pen or color pencil
Answers to Warm Up
Check your work in a different colored pen or color pencil
3n + 5
2n ÷ 7
z-18
6n = 54
n-18 = 23
3n + 5 = 18

5. Shapes & Designs, p. 62

7. 3.1 Building Triangles
Bridges, towers, and many other structures contain many triangles in their design.
What properties of these simple polygons make them valuable in construction? (Discuss with your partner)

8. Critical Thinking…Hmmm…

9. In Class Assignment….S&D 3.1 WS Due Today!
Partners do the following activities:
If possible build a triangle with the side lengths. Sketch/draw your triangle.
Tell whether your triangle is the only one that is possible. Explain
If a triangle is not possible, explain Why.
REMEMBER..it is the space between the hole that represent one unit on the poly strip!!

10. Questions & Answers
What pattern do you see that explains why some sets of #s make a triangle and some do not?
Answer: If the sum of TWO proposed (2 shorter sides) side lengths is less than ( ) the THIRD proposed length, NO triangle can be constructed.
For what side length relationships can you make more than one triangle from a given set of side lengths?
In NO case can a given set of side lengths be used to make 2 different triangle shapes.

11. NOTES:
The sum of the lengths of any TWO sides of a triangle is always greater than the 3rd side. Ex: 2, 6, 7 sum of 2+6= 8 therefore 7(the 3rd side) is less than 8.
Triangle are stable, strong and rigid(unbendable)!
Construction workers use triangles in the construction of roof frames as shown below.
The total sum of the interior angles in a triangle is 180 degrees.
The corner angles of a triangle cannot change without an accompanying change in the length of the edge. Therefore, in order to change a triangle's shape, an edge must collapse.

12. Homework If time start your HW p. 76 #1-5