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Big Ideas Math: Modeling Real Life, Grade 8

BI

Big Ideas Math: Modeling Real Life, Grade 8 View details

Chapter Review

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Exercise 19 Page 132

The sum of the measures of the interior angles of a polygon is (n-2)180, where n represents the number of sides.

1260^(∘)

Practice makes perfect

Let's start by recalling the rule for the sum of the measures of the interior angles of a polygon.

Interior Angle Sum of a Polygon
The sum of the measures of the interior angles of a polygon is (n-2)180, where n represents the number of sides.

Here, we want to find the sum of the interior angle measures of the given polygon. This polygon has 9 sides so it is a 9-gon or nonagon.

To find the sum of the measures of the interior angles of a 9-gon, we will substitute 9 for n in the expression.

(n-2)180

n= 9

( 9-2)180

▼

Evaluate

Subtract term

(7)180

Multiply

1260

The sum of the interior angles of a 9-gon is 1260^(∘).

Subchapter links

1 Parallel Lines and Transversals p.131

2 Angles of Triangles p.132

3 Angles of Polygons p.132-133

4 Using Similar Triangles p.133