1. Find surface areas of spheres.
Find volumes of spheres.
Splash Screen

2. Mathematical Practices
Content Standards
G.GMD.1 Give an informal argument for the formulas for the circumference of a circle, area of a circle, volume of a cylinder, pyramid, and cone.
G.GMD.3 Use volume formulas for cylinders, pyramids, cones, and spheres to solve problems.
Mathematical Practices
1 Make sense of problems and persevere in solving them.
6 Attend to precision.
CCSS

3. great circle
pole
hemisphere
Vocabulary

4. Concept

5. Find the surface area of the sphere. Round to the nearest tenth.
Surface Area of a Sphere
Find the surface area of the sphere. Round to the nearest tenth.
S = 4r2 Surface area of a sphere
= 4(4.5)2 Replace r with 4.5.
≈ Simplify.
Answer: in2
Example 1

6. Find the surface area of the sphere. Round to the nearest tenth.
A in2
B in2
C in2
D in2
Example 1

7. A. Find the surface area of the hemisphere.
Use Great Circles to Find Surface Area
A. Find the surface area of the hemisphere.
Find half the area of a sphere with the radius of 3.7 millimeters. Then add the area of the great circle.
Example 2A

8. Surface area of a hemisphere
Use Great Circles to Find Surface Area
Surface area of a hemisphere
Replace r with 3.7.
≈ 129.0
Use a calculator.
Answer: about mm2
Example 2A

9. Use Great Circles to Find Surface Area
B. Find the surface area of a sphere if the circumference of the great circle is 10 feet.
First, find the radius. The circumference of a great circle is 2r. So, 2r = 10 or r = 5.
Example 2B

10. S = 4r2 Surface area of a sphere = 4(5)2 Replace r with 5.
Use Great Circles to Find Surface Area
S = 4r2 Surface area of a sphere
= 4(5)2 Replace r with 5.
≈ Use a calculator.
Answer: about ft2
Example 2B

11. Use Great Circles to Find Surface Area
C. Find the surface area of a sphere if the area of the great circle is approximately 220 square meters.
First, find the radius. The area of a great circle is r2. So, r2 = 220 or r ≈ 8.4.
Example 2C

12. S = 4r2 Surface area of a sphere ≈ 4(8.4)2 Replace r with 5.
Use Great Circles to Find Surface Area
S = 4r2 Surface area of a sphere
≈ 4(8.4)2 Replace r with 5.
≈ Use a calculator.
Answer: about m2
Example 2C

13. A. Find the surface area of the hemisphere.
A m2
B m2
C m2
D m2
Example 2A

14. B. Find the surface area of a sphere if the circumference of the great circle is 8 feet.
A ft2
B ft2
C ft2
D ft2
Example 2B

15. C. Find the surface area of the sphere if the area of the great circle is approximately 160 square meters.
A. 320 ft2
B. 440 ft2
C. 640 ft2
D. 720 ft2
Example 2C

16. Concept

17. Volumes of Spheres and Hemispheres
A. Find the volume a sphere with a great circle circumference of 30 centimeters. Round to the nearest tenth.
Find the radius of the sphere. The circumference of a great circle is 2r. So, 2r = 30 or r = 15.
Volume of a sphere
(15)3 r = 15
≈ 14,137.2 cm3 Use a calculator.
Example 3A

18. Answer: The volume of the sphere is approximately 14,137.2 cm3.
Volumes of Spheres and Hemispheres
Answer: The volume of the sphere is approximately 14,137.2 cm3.
Example 3A

19. The volume of a hemisphere is one-half the volume of the sphere.
Volumes of Spheres and Hemispheres
B. Find the volume of the hemisphere with a diameter of 6 feet. Round to the nearest tenth.
The volume of a hemisphere is one-half the volume of the sphere.
Volume of a hemisphere
r 3
Use a calculator.
Answer: The volume of the hemisphere is approximately 56.5 cubic feet.
Example 3B

20. A. Find the volume of the sphere to the nearest tenth.
A cm3
B cm3
C cm3
D cm3
Example 3A

21. B. Find the volume of the hemisphere to the nearest tenth.
A m3
B m3
C. 268,082.6 m3
D. 134,041.3 m3
Example 3B

22. Solve Problems Involving Solids
ARCHEOLOGY The stone spheres of Costa Rica were made by forming granodiorite boulders into spheres. One of the stone spheres has a volume of about 36,000 cubic inches. What is the diameter of the stone sphere?
Understand You know that the volume of the stone is 36,000 cubic inches.
Plan First use the volume formula to find the radius. Then find the diameter.
Example 4

23. Solve Volume of a sphere
Solve Problems Involving Solids
Solve Volume of a sphere
Replace V with 36,000.
Divide each side by
Use a calculator to find
2700 ( 1 ÷ 3 )
ENTER 30
The radius of the stone is 30 inches. So, the diameter is 2(30) or 60 inches.
Example 4

24. CHECK You can work backward to check the solution.
Solve Problems Involving Solids
Answer: 60 inches
CHECK You can work backward to check the solution.
If the diameter is 60, then r = 30. If r = 30, then V = cubic inches. The solution is correct. 
Example 4

25. RECESS The jungle gym outside of Jada’s school is a perfect hemisphere
RECESS The jungle gym outside of Jada’s school is a perfect hemisphere. It has a volume of 4,000 cubic feet. What is the diameter of the jungle gym?
A feet
B feet
C feet
D feet
Example 4

26. Homework
Page 884 (10 – 20 Even)
Example 3A