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**Find the area of each circle.**

1. Radius 17 m ANSWER m2 2. Diameter 7.8 in. ANSWER 47.78 in.2

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**Find the volume of each solid.**

3. Cylinder, radius 6 ft, height 10 ft ANSWER ft3 4. Cone, radius 3.1 cm and height 11.8 cm ANSWER cm3

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**5. Find the circumference of a circle with radius 48 m.**

ANSWER m

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**Find the surface area of a sphere**

EXAMPLE 1 Find the surface area of a sphere Find the surface area of the sphere. SOLUTION S = 4πr2 Formula for surface area of a sphere. = 4π(82) Substitute 8 for r. = 256π Simplify. ≈ Use a calculator. The surface area of the sphere is about square inches. ANSWER

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**Standardized Test Practice**

EXAMPLE 2 Standardized Test Practice SOLUTION S = 4πr2 Formula for surface area of a sphere. 20.25π = 4πr2 Substitute 20.25π for S. = r2 Divide each side by 4π. 2.25 = r Find the positive square root.

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EXAMPLE 2 Standardized Test Practice The diameter of the sphere is 2r = = 4.5 centimeters. The correct answer is B. ANSWER

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GUIDED PRACTICE for Examples 1 and 2 1. The diameter of a sphere is 40 feet. Find the surface area of the sphere. The surface area of the sphere is about feet2 ANSWER

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GUIDED PRACTICE for Examples 1 and 2 2. The surface area of a sphere is 30π square meters. Find the radius of the sphere. 2.71 ANSWER

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EXAMPLE 3 Use the circumference of a sphere EXTREME SPORTS In a sport called sphereing, a person rolls down a hill inside an inflatable ball surrounded by another ball. The circumference of the outer ball is 12π feet. Find the surface area of the outer ball. SOLUTION The circumference of the outer sphere is 12π feet, so the radius is = 6 feet. 12π 2π

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EXAMPLE 3 Use the circumference of a sphere Use the formula for the surface area of a sphere. S = 4πr2 = 4π(62) = 144π The surface area of the outer ball is 144π, or about square feet. ANSWER

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GUIDED PRACTICE for Example 3 3. In Example 3, the circumference of the inner ball is 6π feet. Find the surface area of the inner ball. round your answer to two decimal places. ft2 ANSWER

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**Find the volume of a sphere**

EXAMPLE 4 Find the volume of a sphere The soccer ball has a diameter of 9 inches. Find its volume. SOLUTION The diameter of the ball is 9 inches, so the radius is = 4.5 inches. 9 2 V = πr3 4 3 Formula for volume of a sphere = π(4.5)3 4 3 Substitute.

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**Find the volume of a sphere**

EXAMPLE 4 Find the volume of a sphere = 121.5π Simplify. ≈ Use a calculator. The volume of the soccer ball is 121.5π, or about cubic inches. ANSWER

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**Find the volume of a composite solid**

EXAMPLE 5 Find the volume of a composite solid Find the volume of the composite solid. SOLUTION = πr2h – ( πr3) 1 2 4 3 Formulas for volume = π(2)2(2) – π(2)3 2 3 Substitute. 2 3 = 8π – (8π) Multiply.

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**Find the volume of a composite solid**

EXAMPLE 5 Find the volume of a composite solid = π – π 24 3 16 Rewrite fractions using least common denominator. 8 3 = π Simplify. The volume of the solid is π, or about 8.38 cubic inches. 8 3 ANSWER

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GUIDED PRACTICE for Examples 4 and 5 4. The radius of a sphere is 5 yards. Find the volume of the sphere. Round your answer to two decimal places. The volume of the sphere is yd2 ANSWER

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GUIDED PRACTICE for Examples 4 and 5 5. A solid consists of a hemisphere of radius 1 meter on top of a cone with the same radius and height 5 meters. Find the volume of the solid. Round your answer to two decimal places. The volume of the solid is 7.33m2 ANSWER

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Daily Homework Quiz Find the surface area and volume of each sphere. 1. r = 6 ft ANSWER ft2; ft3

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Daily Homework Quiz 2. d = 12.4 m ANSWER m2; m3

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Daily Homework Quiz 3. A great circle of sphere has circumference 16л in.. Find the volume of the sphere. ANSWER in.3

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Daily Homework Quiz 4. Find the radius of a sphere with volume ft3. ANSWER 10.2 ft 5. Find the surface area and volume of the solid. ANSWER m2; m3

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