Download 3.2: Angles of Triangles

3.2: Angles of Triangles
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What are Interior and Exterior
Angles
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Interior Angles are angles inside
a polygon.
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When the sides of a polygon are
extended, other angles are
formed.
S Exterior Angles are the
angles outside of the polygon
that are adjacent to the
interior angles.
Interior Angles Measures of a
Triangle
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The sum of the interior angle
measures of a triangle is 1800
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Algebra
S x+y+z=180
Using Interior Angle Measures
Find the value of x.
Practice
Find the value of x.
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81+25+x=180
106+x=180
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43+x+x-35=180
2x+8=180
2x=172
x=740
x=860
Exterior Angle Measures of a
Triangle
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The measure of an exterior angle
of a triangle is equal to the sum
of the measures of the two
nonadjacent interior angles.
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Algebra
S z=x+y
Finding Exterior Angle
Measures
Find the measure of the exterior angle.
Practice
Find the measure of the exterior angle.
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y=40+30
y=700
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4n-20=n+2n+20
4n-20=3n+20
n-20=20
n=40
Exterior angle= 4(40)-20=160-20=1400
Real Life Application
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An airplane leaves from Miami and
travels around the Bermuda Triangle.
What is the value of x?
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Use what you know about the interior
angle measures of a triangle to write an
equation.