lahge 10 csse cp 470-471.qxd 4/12/09 6:31 am page 470 9...

11
Chapter Chapter 9 9 Surface Area and Volume Surface Area and Volume What shapes are used in a planetarium? Planetariums project images of the night sky onto the inside of a dome. The dome of New York City’s Hayden Planetarium is in the top half of the sphere visible in this photograph. The sphere is built inside a glass cube that houses the Rose Center for Earth and Space at the American Museum of Natural History. Learn More About It You will learn more about the planetarium in Exercises 33–36 on p. 522. r 470

Upload: others

Post on 27-Mar-2020

0 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: LAHGE 10 CSse cp 470-471.qxd 4/12/09 6:31 AM Page 470 9 ...houkgeometry.weebly.com/uploads/8/3/6/8/8368923/ga_9.1_solid_figures_p._470-p._480.pdfthe bases. Then name the solid. a

ChapterChapter 99Surface Area and VolumeSurface Area and Volume

What shapes are used

in a planetarium?

Planetariums project images of the night sky onto the inside of a dome.

The dome of New York City’s Hayden Planetarium is in the top half of the sphere visible in this photograph.

The sphere is built inside a glass cubethat houses the Rose Center for Earth and Space at the American Museum ofNatural History.

Learn More About ItYou will learn more about theplanetarium in Exercises 33–36 on p. 522.

r

470

LAHGE_10_CSse_cp_470-471.qxd 4/12/09 6:31 AM Page 470

Page 2: LAHGE 10 CSse cp 470-471.qxd 4/12/09 6:31 AM Page 470 9 ...houkgeometry.weebly.com/uploads/8/3/6/8/8368923/ga_9.1_solid_figures_p._470-p._480.pdfthe bases. Then name the solid. a

Who usesSurface Area and Volume?

How will you use these ideas?

• Analyze the shape of the first music recordings. (p. 489)• Determine the amount of material needed to make various

objects. (p. 497)• Compare the volumes of swimming pools. (p. 505)• Calculate the amount of food in a pet feeder. (p. 515)• Find the amount of glass in the cube of the Rose Center for

Earth and Space. (p. 522)

AQUARIUM DIVERAquarium divers take careof fish and plants in anaquarium. They monitorthe volume of water in atank and insure that thetank is not overcrowded.(p. 505)

VETERINARIANVeterinarians providetreatment for sick andinjured animals. Theyalso offer preventivecare for healthy animals.(p. 497)

471

LAHGE_10_CSse_cp_470-471.qxd 4/27/09 4:55 PM Page 471

Page 3: LAHGE 10 CSse cp 470-471.qxd 4/12/09 6:31 AM Page 470 9 ...houkgeometry.weebly.com/uploads/8/3/6/8/8368923/ga_9.1_solid_figures_p._470-p._480.pdfthe bases. Then name the solid. a

472 Chapter 9 Surface Area and Volume

Chapter Study GuideStudy Guide99

What’s the chapter about?

• Identifying and naming solids• Finding the surface area of solids• Finding the volume of solids

Key Words

Take this quick quiz. If you are unsure of an answer, look at the

reference pages for help.

Skill Check (refer to pp. 192, 431, 453)

1. What is the length of the hypotenuse in the triangle shown?

�A 13 �B 17

�C 19 �D 169

2. What is the area of the triangle shown above?

�F 15 units2 �G 30 units2 �H 60 units2 �J 120 units2

3. What is the approximate area of the circle?

�A 18.8 in.2 �B 37.7 in.2

�C 113 in.2 �D 226 in.2

PREVIEWPREVIEW

Chapter Readiness QuizPREPAREPREPARE

Drawing Three Dimensional FiguresVISUAL STRATEGYVISUAL STRATEGY

Visualize It!

• solid, p. 473• base, p. 473• face, p. 474• surface area, p. 483

• lateral area, p. 484• height, slant height, p. 491• volume, p. 500• hemisphere, p. 517

Here is a helpfulmethod fordrawing threedimensionalfigures.

6 in.

5

12

Draw the bases. Connect the basesusing vertical lines.

Erase so thathidden edges aredashed lines.

cgpe-09sg 2/8/02 8:27 AM Page 472

Page 4: LAHGE 10 CSse cp 470-471.qxd 4/12/09 6:31 AM Page 470 9 ...houkgeometry.weebly.com/uploads/8/3/6/8/8368923/ga_9.1_solid_figures_p._470-p._480.pdfthe bases. Then name the solid. a

The three-dimensional shapes on this page are examples of solid figures, or . When a solid is formed by polygons, it is called a .

Polyhedra Prisms and pyramids are examples of polyhedra. To namea prism or pyramid, use the shape of the base.

Not Polyhedra Solids with curved surfaces, like the cylinder, cone, and sphere shown below, are not polyhedra.

polyhedronsolids

9.1 Solid Figures 473

Goal

Identify and name solidfigures.

Key Words

• solid

• polyhedron

• base

• face

• edge

9.19.1 Solid Figures

Tell whether the solid is a polyhedron. If so, identify the shape of the bases. Then name the solid.

a. b.

Solution

a. The solid is formed by polygons so it is a polyhedron. The bases are congruent triangles in parallel planes. This figure is a triangular prism.

b. A cylinder has a curved surface, so it is not a polyhedron.

EXAMPLE 111 Identify and Name Polyhedra

VOCABULARY TIP

Poly- means “many”and -hedron is Greekfor “side” or “face.” Apolyhedron is a figurewith many faces. Theplural of polyhedron ispolyhedra.

Student Help

The two of a prismare congruent polygons inparallel planes.

bases The of a pyramidis a polygon.

base

rectangularbases

triangularbase

Sphere Cone Cylinder

Rectangular prism Triangular pyramid

cgpe-0901 8/13/01 12:24 PM Page 473

Page 5: LAHGE 10 CSse cp 470-471.qxd 4/12/09 6:31 AM Page 470 9 ...houkgeometry.weebly.com/uploads/8/3/6/8/8368923/ga_9.1_solid_figures_p._470-p._480.pdfthe bases. Then name the solid. a

Parts of a Polyhedron To avoid confusion, the word side is not used when describing polyhedra. Instead, the plane surfaces are called

and the segments joining the vertices are called . edgesfaces

474 Chapter 9 Surface Area and Volume

Use the diagram at the right.

a. Name the polyhedron.

b. Count the number of faces and edges.

c. List any congruent faces and congruent edges.

Solution

a. The polyhedron is a hexagonal pyramid.

b. The polyhedron has 7 faces and 12 edges.

c. Using the markings on the diagram, you can conclude the following:

Congruent faces Congruent edges

TPQVcTQRVcTRSVc PQ&* c QR&* c RS&* c ST&* c TU&* c UP&*

TSTVcTTUVcTUPV PV&* c QV&* c RV&* c SV&* c TV&* c UV&*

EXAMPLE 222 Find Faces and Edges

Sketch a triangular prism.

Solution

�1 Draw the �2 Connect the �3 Partially erase the triangular bases. corresponding hidden lines to create

vertices of the bases dashed lines. Shade with vertical lines. the prism.

EXAMPLE 333 Sketch a Polyhedron

VISUAL STRATEGY

For more help drawingthree dimensionalfigures, see p. 472.

Student Help

vertex edge

face

P

Q

S

R

TU

V

STUDY TIP

In this book, all of thesolids are right solids.This means that thesegment representingthe height isperpendicular to thebase(s).

Student Help

The trapezoidal faces of this polyhedronare the bases.

cgpe-0901 8/13/01 12:24 PM Page 474

Page 6: LAHGE 10 CSse cp 470-471.qxd 4/12/09 6:31 AM Page 470 9 ...houkgeometry.weebly.com/uploads/8/3/6/8/8368923/ga_9.1_solid_figures_p._470-p._480.pdfthe bases. Then name the solid. a

Tell whether the solid is a polyhedron. If so, identify the shape

of the base(s). Then name the solid.

1. 2. 3.

4. Copy the partial drawing of a triangular pyramid. Then complete the drawing of the pyramid.

9.1 Solid Figures 475

Identify and Sketch Polyhedra

Prism

Rectangular Triangular CubePrism Prism (Square Prism)

Pyramid

Rectangular Triangular PentagonalPyramid Pyramid Pyramid

Cylinder Cone Sphere

TYPES OF SOLIDS

STUDY TIP

In this book, the faces ofa pyramid, not includingthe base, are congruentisosceles triangles,unless otherwise noted.

Student Help

cgpe-0901 8/13/01 12:24 PM Page 475

Page 7: LAHGE 10 CSse cp 470-471.qxd 4/12/09 6:31 AM Page 470 9 ...houkgeometry.weebly.com/uploads/8/3/6/8/8368923/ga_9.1_solid_figures_p._470-p._480.pdfthe bases. Then name the solid. a

In Exercises 1–3, match the solid with its name.

A. prism B. pyramid C. cylinder

1. 2. 3.

In Exercises 4–9, tell whether the statement is true or false. Refer to

the prism below, if necessary.

4. CDHG is a face of the prism.

5. A prism has only one base.

6. ABCD and EFGH are possiblebases of the prism.

7. An edge of the prism is H.

8. GC&* is an edge of the prism.

9. A prism is a polyhedron.

Tell whether the solid is a polyhedron. If so, identify the shape of the

base(s). Then name the solid.

10. 11. 12.

Name the polyhedron. Count the number of faces and edges. List any

congruent faces and congruent edges.

13. 14. 15.

16. How many faces and edges does a box of cerealhave? Visualize It!

M

K

J

T W

VU

LP

P S

R

U XV

F EA

W

D

CB

YZ

Skill Check

Vocabulary Check

Guided Practice

Exercises9.19.1

B

AD

E

F

C

GH

476 Chapter 9 Surface Area and Volume

cgpe-0901 8/13/01 12:24 PM Page 476

Page 8: LAHGE 10 CSse cp 470-471.qxd 4/12/09 6:31 AM Page 470 9 ...houkgeometry.weebly.com/uploads/8/3/6/8/8368923/ga_9.1_solid_figures_p._470-p._480.pdfthe bases. Then name the solid. a

9.1 Solid Figures 477

Name Bases and Solids Tell whether the solid is a polyhedron. If so,

identify the shape of the base(s).Then name the solid.

17. 18. 19.

Logical Reasoning Tell whether the statement is true or false.

20. A rectangular pyramid has two bases.

21. A triangular prism has two bases.

22. The bases of a prism are congruent polygons.

23. A cone has two bases.

24. A sphere is a polyhedron.

Identify Solids Match the solid with its name.

A. cone B. pyramid C. cylinder

D. rectangular prism E. cube F. sphere

25. 26. 27.

28. 29. 30.

Error Analysis Julie incorrectly identified the solid below as

a pyramid with a square base.

31. Correctly identify the solid.

32. What would you say to Julie to help her tell the difference between this solid and a pyramid?

Practice and Applications

Example 1: Exs. 17–19,25–35

Example 2: Exs. 36–38Example 3: Exs. 43–51

Homework Help

Extra Practice

See p. 691.

LAHGE_10_CSse_cp_473-480.qxd 4/6/09 9:33 PM Page 477

Page 9: LAHGE 10 CSse cp 470-471.qxd 4/12/09 6:31 AM Page 470 9 ...houkgeometry.weebly.com/uploads/8/3/6/8/8368923/ga_9.1_solid_figures_p._470-p._480.pdfthe bases. Then name the solid. a

Identify Polyhedra Tell whether the solid is a polyhedron. If so,

identify the shape of the base(s). Then name the solid.

33. 34. 35.

Counting Faces and Edges Name the polyhedron. Then count the

number of faces and edges. List any congruent faces and congruent

edges.

36. 37. 38.

Logical Reasoning Determine whether the statement is true or false.

Explain your reasoning.

39. Prisms, pyramids, cylinders, cones, and spheres are all solids.

40. Prisms, pyramids, cylinders, cones, and spheres are all polyhedra.

41. Every face of a prism is also a base of the prism.

42. Every base of a prism is also a face of the prism.

Copy the partial drawing. Then complete the drawing

of the solid.

43. square pyramid 44. hexagonal prism 45. cylinder

Sketching Solids Sketch the solid described.

46. rectangular prism 47. rectangular pyramid

48. cube 49. cone

50. cylinder 51. sphere

Visualize It!

S

N

T

RP P

J L

FK

H

GA

D

E

C

B

478 Chapter 9 Surface Area and Volume

STUDY TIP

Use a pencil whendrawing solids so thatyou can erase hiddenlines easily.

Student Help

cgpe-0901 8/13/01 12:24 PM Page 478

Page 10: LAHGE 10 CSse cp 470-471.qxd 4/12/09 6:31 AM Page 470 9 ...houkgeometry.weebly.com/uploads/8/3/6/8/8368923/ga_9.1_solid_figures_p._470-p._480.pdfthe bases. Then name the solid. a

9.1 Solid Figures 479

PLATO The solids on thispage are called Platonicsolids, named after the Greek mathematician andphilosopher Plato. The imageof Plato above is a detail ofThe School of Athens(1509–10) by Raphael.

History

Mathematician Leonhard Euler proved that the number of faces (F),vertices (V ), and edges (E) of a polyhedron are related by the formula F � V � E � 2.

Use Euler’s Formula to find the number of vertices on the tetrahedron shown.

SolutionThe tetrahedron has 4 faces and 6 edges.

F � V � E � 2 Write Euler’s Formula.

4 � V � 6 � 2 Substitute 4 for F and 6 for E.

4 � V � 8 Simplify.

V � 8 � 4 Subtract 4 from each side.

V � 4 Simplify.

ANSWER � The tetrahedron has 4 vertices.

EXAMPLE Euler’s Formula

faceedge

vertices

Platonic Solids A Platonic solid has faces that are congruent, regular

polygons. Use the example above to find the number of vertices on

the Platonic solid.

52. cube 53. octahedron6 faces, 12 edges 8 faces, 12 edges

54. dodecahedron 55. icosahedron12 faces, 30 edges 20 faces, 30 edges

Using Algebra Use Euler’s Formula to find the number of faces,

edges, or vertices. Use the example above as a model.

56. A prism has 5 faces and 6 vertices. How many edges does it have?

57. A pyramid has 12 edges and 7 vertices. How many faces does it have?

58. A prism has 8 faces and 12 vertices. How many edges does it have?

cgpe-0901 8/13/01 12:24 PM Page 479

Page 11: LAHGE 10 CSse cp 470-471.qxd 4/12/09 6:31 AM Page 470 9 ...houkgeometry.weebly.com/uploads/8/3/6/8/8368923/ga_9.1_solid_figures_p._470-p._480.pdfthe bases. Then name the solid. a

480 Chapter 9 Surface Area and Volume

59. Multiple Choice How many faces does the prism below have?

�A 2 �B 3

�C 4 �D 5

60. Multiple Choice How many edges does the pyramid at the right have?

�F 6 �G 5

�H 4 �J 3

61. Multiple Choice How many vertices does the pyramid above have?

�A 6 �B 5 �C 4 �D 3

Finding Measures of Squares and Rectangles Use the given

information to find the missing measure. (Lesson 8.3)

62. A square has a side length of 9 centimeters. Find its area.

63. A rectangle has a height of 4 meters and a base length of 7 meters.Find its area.

64. A rectangle has an area of 60 square inches and a height of 6 inches.Find the length of its base.

65. A square has an area of 169 square feet. Find its side length.

Finding Circumference and Area of a Circle Find the circumference

and the area of the circle. Round your answers to the nearest whole

number. (Lesson 8.7)

66. 67. 68.

Evaluating Expressions Evaluate the expression.

(Skills Review, p. 670)

69. 92 � (12 � 39) 70. 8 � 4 p 3 � 5 71. (7 � 5) p 14

72. 10 � (5 � 2)2 � 8 73. 14 � 42 � 26 74. 3(10 � 3)2

Substituting and Simplifying Expressions Evaluate the expression

when l � 3, h � 5, and w � 2. Write your answer in terms of π,

if appropriate. (Skills Review, p. 674)

75. l pw p h 76. 2l� 2w � 2h 77. 2πh

78. πw 2h 79. πl2 80. 2l� 2w

Algebra Skills

14 yd

5 cm

12 ft

Mixed Review

Standardized Test

Practice

cgpe-0901 8/13/01 12:24 PM Page 480