draw a concave pentagon. draw a convex irregular heptagon. 2-2 day 2 10... · 2017. 10. 25. ·...
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Draw a concave pentagon.
Draw a convex irregular heptagon.
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REMEMBER: By the Triangle Sum Theorem, the sum of the interior angle
measures of a triangle is 180°.
Using triangles, what's the sum of the interior angles of each figure?
What do you notice?
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Number of sides
Number of triangles
Sum of Interior Angles
Measure of one interior angle (Regular Polygon only)
n
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Theorem 2-3
Polygon Interior Angle-Sum Theorem
The sum of the interior angle measures of a convex polygon with n sides is (n - 2) 180°.
http://www.mathopenref.com/polygoninteriorangles.html
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1. Find the sum of the interior angle measures of a...
convex heptagon.
regular 16gon.
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In a regular polygon with n sides the measure of one interior angle is
(n - 2)180n
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2. What is each measure of the interior
angle of a regular 18gon?
What is each interior angle of a dodecogon?
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91°79°
x 125°
3. Find the measure of the missing angle of the quadrilateral.
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In the polygons below, an exterior angle has been measured at each vertex. Notice that in each case, the sum of the exterior angle
measures is 360°.
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Exterior Angles
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Theorem 2-4
Polygon Exterior Angle-Sum Theorem
The sum of the measures of the exterior angles of a polygon, one at each vertex, is 360°.
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4. Find the measure of each exterior angle of a regular 20gon.
NOTE: One exterior angle of a regular polygon with n sides = 360
n
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5. Find the value of b in polygon FGHJKL.
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6. Ann is making paper stars for party decorations. What is the measure of ∠1?
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7. Find the measure of each interior angle of pentagon
ABCDE. You will have to find the value of c.
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8. The measure of an exterior angle of a regular polygon is 60°. Find the number of sides.
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HW # 20
p. 7980 # 14,1017,1926
Quiz on Friday !!!!