Download 2-25-13 notes triangles and polygons

Unit 3 and unit 4
Do Now 2-25-13
• Solve for x in both problems
• 2 x + 7 = 13
3x - 10
X + 40
Congruence & Triangles
• Introduction to Congruent Triangles
• Draw a large triangle
– What is the sum of the angle measures of the
triangle? No protractors
– Tear off and rearrange the three corners of the
triangle, then form a straight angle; what do you
notice
Exterior angles and interior angles of
shapes
• Triangle Angle Sum Theorem
Sum of the measures of the angles of a triangle is
180
– Pg. 172
www.kz.com or pg. 173
• Exterior Angle of a polygon – 2 far angles equal
the outside one. (see example)
• Pg. 175 #16
• Remote interior angles
Practice exterior with triangles
• Pg. 176 #18, 20, #26, 27
• Pg. 177 #33
Exterior angles with
polygons/quadrilaterals
• Pg. 352 activity (investigate 3 bullets and
question #1)
• What is the sum of the exterior angles of
polygons?
• 360
• What conclusion can be made about the
interior and exterior angles of a polygon at
each of its vertices?
– Supplementary
Polygon angle sum theorem
• The sum of the measures of the interior
angles of an n-gon is (n-2)180
• Example pg. 355 problem 3, #3
what is measure of angle G in quadrilateral
EFGH?
• Polygon exterior angle sum theorem = sum of
the measures of the exterior angles of a
polygon, one at each vertex is 360
independent
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Pg. 356 #7, 15,
Pg. 357 #28, 30
Pg. 358 #47
How do quadrilaterals, congruent triangles,
and parallel lines coincide? Or have a
relationship together?
Summary 2-25-13
• What is the connection between parallel lines
and triangles?