Download 8.6.2: Interior Angle Sums

8.6.2: Interior Angle Sums
1. Complete the chart.
Diagram
Number
of sides
Sum of
interior angles
Understanding
The sum of the angles in any triangle is
180o.
3
180
4
5
n
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.
TIPS4RM: Grade 9 Applied – Unit 8: Plane Geometry
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8.6.2: Interior Angle Sums (continued)
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 interior angles of the deck.
Show your work.
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?
TIPS4RM: Grade 9 Applied – Unit 8: Plane Geometry
32