MFM 1PI ­ U8 ­ D5 ­ Interior and Exterior angles in po.notebook
May 13, 2016
MFM 1PI
Interior and Exterior Angle Sums
Teacher notes: I would use the exterior angles GSP file to demonstrate the sum of exterior angles.
Once students recognize that the sum of angles in a triangle(page 1 of the GSP file Interior angles), have them subdivide each polygon into triangles by extending a line from one vertex to each of the remaining vertices. Then ask students how to connect the # of triangles to the sum of interior angles. I would only use the rest of the GSP file on interior angles as proof of their prediction.
exterior angles
Interior angles
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MFM 1PI ­ U8 ­ D5 ­ Interior and Exterior angles in po.notebook
May 13, 2016
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MFM 1PI ­ U8 ­ D5 ­ Interior and Exterior angles in po.notebook
May 13, 2016
MFM 1PI – U8 ­ 5 ­ Interior and Exterior angles in polygons
180x1=180
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180x2=360
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180x3=540
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# of sides -2
180x4=720
=180x(n-2)
360
360
360
360
360
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MFM 1PI ­ U8 ­ D5 ­ Interior and Exterior angles in po.notebook
May 13, 2016
GENERAL RULE:
For a polygon with n sides, the sum of INTERIOR angles is given by the formula:
Sum =180x(#of triangles) or Sum =180(n-2)
For any polygon the sum of EXTERIOR angles is always _________.
360
2. a) Determine the sum of the interior angles in a polygon with 15 sides. Show your work.
b) Determine the number of sides in a polygon if the sum of the interior angles is 5400°. Show your work.
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MFM 1PI ­ U8 ­ D5 ­ Interior and Exterior angles in po.notebook
May 13, 2016
3. Derek is building a deck for his summer job in the shape of a regular octagon.
a) Define: regular octagon
b) Determine the measure of the sum of the interior angles of the deck. Show your work.
c) Determine the measure of one angle in the octagon
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MFM 1PI ­ U8 ­ D5 ­ Interior and Exterior angles in po.notebook
May 13, 2016
4. A Canadian $1 coin, known as a loonie, is a regular polygon with 11 sides, called an undecagon.
a) Define a regular polygon with 11 sides.
b) Determine the sum of the interior angles of the loonie.
c)
What is the size of one of the interior angles? practice pg 101 #2-6
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Attachments
POLYANGLES.GSP
TIPS4RManglespolygonrevised.gsp
MFM 1PI ­ U8 ­ D5 ­ POLYANGLES﴾25899﴿.GSP