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Pearson Geometry Common Core, 2011

PG

Pearson Geometry Common Core, 2011 View details

3. Areas of Regular Polygons

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Exercise 44 Page 634

The area of a regular polygon is half the product of the apothem and the perimeter.

B

Practice makes perfect

We want to find the area of a regular pentagon with an apothem that measures 25.1mm and a perimeter of 182mm. Recall that the area of a regular polygon is half the product of the apothem and the perimeter.

To find the area of the polygon we will substitute a= 25.1mm and p=182mm in the formula A= 12ap and evaluate.

A=1/2ap

a= 25.1, p= 182

A=1/2( 25.1)(182)

▼

Evaluate right-hand side

Multiply

A=1/2(4568.2)

a = 10* a/10

A=1/2(45 682/10)

Multiply fractions

A=45 682/20

Calculate quotient

A=2284.1

The area of a regular pentagon is 2284.1mm^2, which corresponds to answer B.

Subchapter links

Lesson Check p.631

Practice and Problem-Solving Exercises p.632-634

Standardized Test Prep p.634

Mixed Review p.634