In Our Everyday Lives

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Geometry

• In Our Everyday Lives

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Triangles
1.Triangles are polygons with three
sides. 2.Triangles are popular in construction
because they are rigid. 3.Triangles and the
measures of their angles appear everywhere
around us. Can you think of some examples?
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EXAMPLES...
Guyanas Flag
Transamerica Building
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Parts of a Triangle
C
vertex
height
B
A
base
Any side of a triangle can be called the base.
The line segment that starts at a vertex and is
perpendicular base is called the height.
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How do you name a Triangle?
C
This is one of my names!
B
A
ABC
To name a triangle, name the vertices in either
clockwise or counterclockwise order.
Try to name this triangle in six different ways!
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Classifying Triangles by their Sides
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Classifying Triangles by their Angles
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HOW WOULD YOU CLASSIFY THE TRIANGLE BELOW?
Please explain your answer._______________________
__ _______________________________________________
_______________________________________________
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Work Together
Investigating Angles of a Triangle
Step 1 Draw three large triangles on a sheet of
paper.
Step 2 Use a protractor to find the measures
of the angles of the triangles.
Step 3 Take each triangle separately and add
its angle measures.
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Work Together
CONTINUED.
Next Compare the results of your group. Make a
conjecture about the sum of the
angles.______________________ ____________________
_____________ _________________________________ __
_______________________________
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The measures of the angles of a triangle total
180
35
60
90
30
76
69
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Assessment
Use a ruler and a protractor to draw triangles to
support your answers!
1. Can an isosceles triangle be a right
triangle?
2. Can a scalene triangle be an acute triangle?
Click the check mark for more assessment
questions.
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3. Can a right triangle be an equilateral
triangle?
4. One angle of an isosceles triangle has the
measure 120.Find the measure of the two congruent
angles.
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Challenge!!
Can you add one more triangle to make five
triangles in this picture?
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Just for Fun...

• What do you call an angle which is adorable?

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Answer
Acute Angle
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EXPLORE ON YOUR OWN..
http//fpl.thinkquest.org/J002441F
http//forum.swarthmore.edu/geopow/