1. Find the surface area of the cone. Round to the nearest tenth.
2. Find the surface area of a cone
with a radius of 6 feet and a
slant height of 10 feet. Round to
the nearest tenth.
3. Find the slant height of a cone with a radius of 4 centimeters and a surface area of 48 square centimeters.
Lesson 6 Menu

2. Recognize and define basic properties of spheres.
Find surface areas of spheres.
great circle
hemisphere
Lesson 6 MI/Vocab

3. Spheres and Circles
In the figure, O is the center of the sphere, and plane P intersects the sphere in circle R. If OR = 6 centimeters and OS = 14 centimeters, find RS.
Lesson 6 Ex1

4. Subtract 36 from each side.
Spheres and Circles
The radius of circle R is segment and S is a point on circle R and on sphere O. Use the Pythagorean Theorem for right triangle ORS to solve for RS.
Pythagorean Theorem
Simplify.
Subtract 36 from each side.
Use a calculator.
Answer: RS is approximately 12.6 centimeters.
Lesson 6 Ex1

5. In the figure, O is the center of the sphere, and plane U intersects the sphere in circle L. If OL = 3 inches and LM = 8 inches, find OM to the nearest tenth.
A. 7.4 in.
B. 8.5 in.
C. 11 in.
D. 8.7 in. A B C D
Lesson 6 CYP1

6. Lesson 6 KC1

7. Surface area of a sphere
A. Find the surface area of the sphere, given a great circle with an area of approximately square centimeters.
The surface area of a sphere is four times the area of the great circle.
Surface area of a sphere
Multiply.
Answer: The surface area is approximately square centimeters.
Lesson 6 Ex2

8. B. Find the surface area of a hemisphere with a radius of 3.8 inches.
A hemisphere is half of a sphere. To find the surface area, find half of the surface area of the sphere and add the area of the great circle.
Surface area of a hemisphere
Substitution
Use a calculator.
Answer: The surface area is approximately square inches.
Lesson 6 Ex2

9. A. Find the approximate surface area of the sphere, given a great circle with an area of approximately 91.6 square centimeters.
A cm2
B cm2
C cm2
D cm2 A B C D
Lesson 6 CYP2

10. B. Find the approximate surface area of a hemisphere with a radius of 6.4 inches.
A in2
B in2
C in2
D in2 A B C D
Lesson 6 CYP2

11. First, find the radius of the sphere.
Find the surface area of a ball with a circumference of 24 inches to determine approximately how much leather is needed to make the ball.
First, find the radius of the sphere.
Circumference of a circle
C = 24
Divide each side by
Use a calculator.
Lesson 6 Ex3

12. Surface area of a sphere
Next, find the surface area of the sphere. Be sure to round to the nearest tenth.
Surface area of a sphere
Use a calculator.
Answer: The surface area is approximately square inches.
Lesson 6 Ex3

13. Find the surface area of a ball with a circumference of 18 inches to determine how much leather is needed to make the ball.
A in2
B in2
C in2
D in2 A B C D
Lesson 6 CYP3