look for a pattern in the last column of the table. what...
TRANSCRIPT
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Question: What is the sum of the measures of the interior angles of a convex ngon? Recall: an ngon is a polygon with n sides and n vertices
Exploration: Find sums of interior angle measures.Step 1: Draw convex polygons with three sides, four sides, five sides and six sides.
Step 2: In each polygon, draw all the diagonals from one vertex. A diagonal is a segment that joins two nonconsecutive vertices. Notice that the diagonals divide the polygon into triangles.
Step 3: Complete the table below.
Polygon Number of Sides
Number of Triangles
Sum of measures of interior angles
Triangle 3 1
Quadrilateral
Pentagon
Hexagon
n gon n
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Draw Conclusions: Use your observations to complete these exercises.
1. Look for a pattern in the last column of the table. What is the sum of the measures of the interior angles of a convex heptagon? a convex octagon?
2. Do the side lengths affect the sum of the interior angle measures of a hexagon? Explain.
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8.1 Find Angle Measures in Polygons
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Polygon Interior Angles Theorem
The sum of the measures of the interior angles of a convex ngon is _______________(n 2) 180.
Interior Angles of a Quadrilateral
The sum of the measures of the interior angles of a quadrilateral is 360o
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Find the sum of the measures of the interior angles of a convex octagon.
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The sum of the measures of the interior angles of a convex polygon is 900o. Classify the polygon by the number of sides.
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Find the value of x in the diagram shown.
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Find the value of x in the diagram shown.
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Unlike the sum of the interior angle measures of a convex polygon, the sum of the exterior angle measures does NOT depend on the number of sides of the polygon.
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Polygon Exterior Angles Theorem
The sum of the measures of the exterior angles of a convex polygon, one angle at each vertex, is 360o.
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Find the value of x.
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~ ~ ~ Classwork ~ ~ ~
2. The trampoline shown is shaped like a regular dodecagon (12 sides). Find (a) the measure of each interior angle and (b) the measure of each exterior angle.
3. An interior angle and an adjacent exterior angle of a polygon form a linear pair. How can you use this fact as another method to find the exterior angle measure of the trampoline?
1. The outline of the playing field at a baseball park is a polygon, as shown. Find the sum of the measures of the interior angles of the polygon.
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Take out your student handbook and write downthe homework assignment:
pg. 510511 #315 odd, 24, 25