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Area, Volume, and Surface Area

Section 9.3

Slide 2Copyright © 2015, 2011, 2008 Pearson Education, Inc.

Finding Areas of Geometric Figures

Area Formulas of Common Geometric Figures

Rectangle

width

length

Area = length · width

A = lw

Square

side

side

Area = side · side

A = s ·s = s2

Slide 3Copyright © 2015, 2011, 2008 Pearson Education, Inc.

Finding Areas of Geometric Figures

Area Formulas of Common Geometric Figures

Triangle Parallelogram

Area = base · height1Area = base height

2

1

2A b h

A = b · h

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Finding Areas of Geometric Figures

Area Formulas of Common Geometric Figures

Trapezoid

1Area = (one base other Base) height

2

1 = ( )

2A b B h

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Example

Find the area of a triangle.6 yds

5 yds

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Example

Find the area.

ft4

15

ft7

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Example

Find the area.5 m

9 m

4 m

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Circles

Area Formula of a Circle

2Area (radius) radius

2A r

22(A fraction approximation for is .)

7

(A decimal approximation for is 3.14.)

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Example

Find the area of the circle.

2 cm

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Formulas

2 2 2SA lh wh lw

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Example

Find the volume.

4 cm

4 cm8 cm

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Example

Find the surface area.4 cm

4 cm8 cm

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Formulas

26SA s

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Formulas

24SA r

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ExampleApproximate the volume of the ball with a 3 inch radius. Use the approximation Give an exact answer and an approximate answer.

24

3V r

22 for .

7

Exact Approximate

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Finding Formulas Solids

22 2SA rh r

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Example

Approximate the volume of the can. Use Give an exact volume and an approximate volume.

22 for .

7

Exact

continued

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Formulas

2 2 2SA r r h r

1

2SA B pl

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Example

Approximate the volume of the cone. Use Give an exact answer and an approximate answer.

3.14 for .

21

3V r h

Approximate

213 cm 14 cm

3

42 cu cm

continued

Slide 20Copyright © 2015, 2011, 2008 Pearson Education, Inc.

continued

Approximate the volume of the cone. Use Give an exact answer and an approximate answer.

3.14 for .