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Section 12-6 Surface Areas and Volumes of Spheres
50

Geometry Section 12-6

Jan 22, 2018

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Page 1: Geometry Section 12-6

Section 12-6Surface Areas and Volumes of Spheres

Page 2: Geometry Section 12-6

Essential Questions

How do you find surface areas of spheres?

How do you find volumes of spheres?

Page 3: Geometry Section 12-6

Vocabulary

1. Great Circle:

2. Pole:

3. Hemisphere:

Page 4: Geometry Section 12-6

Vocabulary

1. Great Circle:

2. Pole:

3. Hemisphere:

A circle formed when a plane intersects a sphere and the circle has the same center as the sphere

Page 5: Geometry Section 12-6

Vocabulary

1. Great Circle:

2. Pole:

3. Hemisphere:

A circle formed when a plane intersects a sphere and the circle has the same center as the sphere

The endpoints of the diameter of a great circle

Page 6: Geometry Section 12-6

Vocabulary

1. Great Circle:

2. Pole:

3. Hemisphere:

A circle formed when a plane intersects a sphere and the circle has the same center as the sphere

The endpoints of the diameter of a great circle

One of the two congruent halves of a sphere created by a great circle

Page 7: Geometry Section 12-6

Formulas

Surface Area of a Sphere:

Volume of a Sphere:

Page 8: Geometry Section 12-6

Formulas

Surface Area of a Sphere: SA = 4π r2

Volume of a Sphere:

Page 9: Geometry Section 12-6

Formulas

Surface Area of a Sphere: SA = 4π r2

Volume of a Sphere: V = 43π r3

Page 10: Geometry Section 12-6

Example 1Find the surface area of the sphere.

Page 11: Geometry Section 12-6

Example 1Find the surface area of the sphere.

SA = 4π r2

Page 12: Geometry Section 12-6

Example 1Find the surface area of the sphere.

SA = 4π r2

SA = 4π (4.5)2

Page 13: Geometry Section 12-6

Example 1Find the surface area of the sphere.

SA = 4π r2

SA = 4π (4.5)2

SA ≈ 254.47 in2

Page 14: Geometry Section 12-6

Example 2Find the surface area of a hemisphere with a diameter of 8 mm to the nearest hundredth.

Page 15: Geometry Section 12-6

Example 2Find the surface area of a hemisphere with a diameter of 8 mm to the nearest hundredth.

SA = 12 i4π r

2 + π r2

Page 16: Geometry Section 12-6

Example 2Find the surface area of a hemisphere with a diameter of 8 mm to the nearest hundredth.

SA = 12 i4π r

2 + π r2 r = 12 d

Page 17: Geometry Section 12-6

Example 2Find the surface area of a hemisphere with a diameter of 8 mm to the nearest hundredth.

SA = 12 i4π r

2 + π r2 r = 12 d

r = 12 (8)

Page 18: Geometry Section 12-6

Example 2Find the surface area of a hemisphere with a diameter of 8 mm to the nearest hundredth.

SA = 12 i4π r

2 + π r2 r = 12 d

r = 12 (8)

r = 4 mm

Page 19: Geometry Section 12-6

Example 2Find the surface area of a hemisphere with a diameter of 8 mm to the nearest hundredth.

SA = 12 i4π r

2 + π r2 r = 12 d

r = 12 (8)

r = 4 mm

SA = 2π (4)2 + π (4)2

Page 20: Geometry Section 12-6

Example 2Find the surface area of a hemisphere with a diameter of 8 mm to the nearest hundredth.

SA = 12 i4π r

2 + π r2 r = 12 d

r = 12 (8)

r = 4 mm

SA = 2π (4)2 + π (4)2

SA ≈150.8 mm2

Page 21: Geometry Section 12-6

Example 3Find the surface area of a sphere if the

circumference of the great circle is 14π inches.

Page 22: Geometry Section 12-6

Example 3Find the surface area of a sphere if the

circumference of the great circle is 14π inches.

SA = 4π r2

Page 23: Geometry Section 12-6

Example 3Find the surface area of a sphere if the

circumference of the great circle is 14π inches.

SA = 4π r2 C = 2π r

Page 24: Geometry Section 12-6

Example 3Find the surface area of a sphere if the

circumference of the great circle is 14π inches.

SA = 4π r2 C = 2π r14π = 2π r

Page 25: Geometry Section 12-6

Example 3Find the surface area of a sphere if the

circumference of the great circle is 14π inches.

SA = 4π r2 C = 2π r14π = 2π r2π 2π

Page 26: Geometry Section 12-6

Example 3Find the surface area of a sphere if the

circumference of the great circle is 14π inches.

SA = 4π r2 C = 2π r14π = 2π r2π 2πr = 7 in.

Page 27: Geometry Section 12-6

Example 3Find the surface area of a sphere if the

circumference of the great circle is 14π inches.

SA = 4π r2 C = 2π r14π = 2π r2π 2πr = 7 in.

SA = 4π (7)2

Page 28: Geometry Section 12-6

Example 3Find the surface area of a sphere if the

circumference of the great circle is 14π inches.

SA = 4π r2 C = 2π r14π = 2π r2π 2πr = 7 in.

SA = 4π (7)2

SA ≈ 615.75 in2

Page 29: Geometry Section 12-6

Example 4Find the volume of the sphere rounded to the

nearest hundredth.

Page 30: Geometry Section 12-6

Example 4Find the volume of the sphere rounded to the

nearest hundredth.

V = 43π r3

Page 31: Geometry Section 12-6

Example 4Find the volume of the sphere rounded to the

nearest hundredth.

V = 43π r3

V = 43π (4.5)3

Page 32: Geometry Section 12-6

Example 4Find the volume of the sphere rounded to the

nearest hundredth.

V = 43π r3

V = 43π (4.5)3

V ≈ 381.70 in3

Page 33: Geometry Section 12-6

Example 5Find the volume of a hemisphere with a diameter

of 6 feet to the nearest hundredth.

Page 34: Geometry Section 12-6

Example 5Find the volume of a hemisphere with a diameter

of 6 feet to the nearest hundredth.

V = 12i43π r3

Page 35: Geometry Section 12-6

Example 5Find the volume of a hemisphere with a diameter

of 6 feet to the nearest hundredth.

V = 12i43π r3 r = 1

2 d

Page 36: Geometry Section 12-6

Example 5Find the volume of a hemisphere with a diameter

of 6 feet to the nearest hundredth.

V = 12i43π r3 r = 1

2 d

r = 12 (6)

Page 37: Geometry Section 12-6

Example 5Find the volume of a hemisphere with a diameter

of 6 feet to the nearest hundredth.

V = 12i43π r3 r = 1

2 d

r = 12 (6)

r = 3 ft

Page 38: Geometry Section 12-6

Example 5Find the volume of a hemisphere with a diameter

of 6 feet to the nearest hundredth.

V = 12i43π r3 r = 1

2 d

r = 12 (6)

r = 3 ftV = 23π (3)3

Page 39: Geometry Section 12-6

Example 5Find the volume of a hemisphere with a diameter

of 6 feet to the nearest hundredth.

V = 12i43π r3 r = 1

2 d

r = 12 (6)

r = 3 ftV = 23π (3)3

V ≈ 56.55 ft3

Page 40: Geometry Section 12-6

Example 6Find the volume of a sphere that has a great

circle with an area of 9π square feet.

Page 41: Geometry Section 12-6

Example 6Find the volume of a sphere that has a great

circle with an area of 9π square feet.

V = 43π r3

Page 42: Geometry Section 12-6

Example 6Find the volume of a sphere that has a great

circle with an area of 9π square feet.

V = 43π r3 A = π r2

Page 43: Geometry Section 12-6

Example 6Find the volume of a sphere that has a great

circle with an area of 9π square feet.

V = 43π r3 A = π r2

9π = π r2

Page 44: Geometry Section 12-6

Example 6Find the volume of a sphere that has a great

circle with an area of 9π square feet.

V = 43π r3 A = π r2

9π = π r2π π

Page 45: Geometry Section 12-6

Example 6Find the volume of a sphere that has a great

circle with an area of 9π square feet.

V = 43π r3 A = π r2

9π = π r2π π

9 = r2

Page 46: Geometry Section 12-6

Example 6Find the volume of a sphere that has a great

circle with an area of 9π square feet.

V = 43π r3 A = π r2

9π = π r2π π

r = 3 ft.9 = r2

Page 47: Geometry Section 12-6

Example 6Find the volume of a sphere that has a great

circle with an area of 9π square feet.

V = 43π r3 A = π r2

9π = π r2π π

r = 3 ft.9 = r2

V = 43π (3)3

Page 48: Geometry Section 12-6

Example 6Find the volume of a sphere that has a great

circle with an area of 9π square feet.

V = 43π r3 A = π r2

9π = π r2π π

r = 3 ft.9 = r2

V = 43π (3)3

V ≈113.10 ft3

Page 49: Geometry Section 12-6

Problem Set

Page 50: Geometry Section 12-6

Problem Set

p. 868 #1-25 odd

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