Triangle Theorems
Presentation
•
Mathematics
•
7th Grade
•
Practice Problem
•
Medium
Standards-aligned
Payton Sullivan
Used 133+ times
FREE Resource
7 Slides • 6 Questions
1
Triangle Rules
2
Here are the rules about triangles:
ALL angles need to add up to be 180 degrees! No matter what!
The 3rd side of a triangle needs to be smaller than the sum of your two shorter sides.
If you do not meet either of these rules, IT ISN'T A TRIANGLE!
3
Multiple Choice
I have a triangle that has the angle measurements 60 and 40 degrees. What has to be my third angle?
60
40
80
100
4
Sides:
Use this:
small side + small side = C
C > third side
5
Example:
I have the sides 2 ft, 2 ft, and 4 ft.
Add your two shortest sides: 2 + 2
2 + 2 is 4. Is my third side smaller than 4?
NO! This will not be a triangle. A good option for a 3rd side could be 3 ft or 2 ft. 4ft is too wide!
6
Multiple Choice
My triangle has these side lengths:
6 ft, 7ft, 8ft
Is this a triangle?
Yes! The sum of my two smallest sides is 13 and 8 is smaller than 13. IT WORKS!
No!! It doesn't follow the rules!
7
How many triangles?
Unique Triangles
Many Triangles
None
8
Unique Triangles
If you are given sides, you cannot do anything to change the triangle.
Sides are very strict boundaries. You will only be able to make ONE triangle that is unique.
MAKE SURE YOUR SIDES FOLLOWS THE RULES!
9
Many Triangles
Angles are very flexible! If you are given angles with no side lengths to use, you can make as many triangles as you want!
You can change the lengths of the sides without changing the angles.
Make sure all of your angles add up to be 180!
10
Multiple Choice
I have a triangle that has sides 3 inches, 5 inches, and 7 inches. I can make...
One unique triangle
Many triangles
This isn't a triangle
11
Multiple Choice
I have a triangle who's angles are 40, 50, and 90 degrees. I can make
One unique triangle
Many triangles
This is not a triangle
12
Multiple Choice
I have a triangle that has the angles 30, 50, and 50. I can make...
One unique triangle
Many triangles
This isn't a triangle!
13
Multiple Select
Let's review:
Triangles need:
Angles that will add up to equal 180 degrees
Angles to equal 90 degrees
Third side to be BIGGER than the sum of your two smallest sides.
Third side to be SMALLER than the sum of your two smallest sides.
Triangle Rules
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