Triangle Shapes
A
B
C
D
G
F
E
H
8.G.A.5 Student Resource
I
Similar Triangles
J
K
L
O
8.G.A.5 Student Resource
M
N
Parallel Lines
2
1
3
4
5
8
7
6
10
11
9
12
13
14
8.G.A.5 Student Resource
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15
Name__________________________________________ Period______________ Date________________
Triangle Shapes Exploration 1: Interior Angles
A
Like this:
1. Using a sheet of Patty Paper, trace Angle A, Angle B, and Angle C
separately on the first triangle and label each vertex.
2. Cut around each angle (including the label). You should cut an
area around the whole angle, not along the lines.
B
3. Arrange the angles in various ways. Overlap them, etc.
Record your observations:
Repeat steps 1, 2, and 3 above for triangle DEF.
Record your observations:
Repeat steps 1, 2, and 3 above for triangle GHI.
Record your observations:
Using mathematical vocabulary, draw conclusions about the sum of the interior
angles of triangles:
8.G.A.5 Student Resource
C
Name____________________________________________ Period_________________ Date____________
Triangle Shapes Exploration 2: Exterior Angles
1. Extend each side of triangle A in one direction.
Be sure to use a ruler.
2. Using a sheet of Patty Paper, trace the newly formed
exterior angles as you did in the first exploration.
Like this:
A
A
C
C
3. Cut around each angle. You should cut an
area around the whole angle, not along the lines.
4. Arrange the angles in various ways. Overlap them, etc.
Record your observations:
Repeat steps 1 - 4 above for triangle DEF.
Record your observations:
Repeat steps 1 - 4 above for triangle GHI.
Record your observations:
Using mathematical vocabulary, draw conclusions about the sum of the exterior
angles of triangles:
8.G.A.5 Student Resource
B
B
Name____________________________________________ Period______________ Date_______________
Similar Triangles Exploration
1. Using Patty Paper, trace triangle JKL, including labels
2. How does triangle JKL compare to triangle MNO?
What is the same?

What is different?
3. Using mathematical vocabulary, draw conclusions about the angles and sides of
similar triangles.
4. What is the minimum number of angle measurements needed to produce a
triangle similar to another triangle? That is, if you are given just one angle, will all
triangles containing that angle be similar? What if you have two angle
measurements? All three? Use a ruler, Patty Paper, and/or a protractor to help you
determine your answer.
8.G.A.5 Student Resource
Name_______________________________________ Period____________ Date________________
Parallel Lines Exploration
Using Patty Paper, explore the relationships that exist between angles 1-8.
Record your observations:
Using Patty Paper, explore the relationships that exist between angles 9-16.
Record your observations:
Using mathematical vocabulary, draw conclusions about the angles formed when
two parallel lines are cut by a transversal.
8.G.A.5 Student Resource