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2(3.14)( 11 ). ANSWER. The circumference is about 69.08 meters. EXAMPLE 1. Using Radius to Find Circumference. Find the circumference of a circle with a radius of 11 meters. SOLUTION. C = 2π r. Circumference formula. Substitute 3.14 for π and 11 for r. = 69.08. Multiply.
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2(3.14)(11) ANSWER The circumference is about 69.08 meters. EXAMPLE 1 Using Radius to Find Circumference Find the circumference of a circle with a radius of 11 meters. SOLUTION C = 2πr Circumference formula Substitute 3.14 for π and 11 for r. = 69.08 Multiply.
Find the circumference of the circle. . 213 2271 227 Substitute. Use for π because 21 is divisible by 7. ANSWER The circumference is about 66feet. EXAMPLE 2 Using Diameter to Find Circumference SOLUTION The measure shown is a diameter, so use the circumference formula that involves the diameter. C = πd Circumference formula = 66 Multiply
423.9 3.14d 423.9 3.14 3.14d 3.14 = The diameter is about 135 feet. The correct answer is C. ANSWER EXAMPLE 3 Standardized Test Practice SOLUTION You are asked to find the diameter, so use the circumference formula that involves diameter. C = πd Circumference formula Substitute 423.9 for Cand 3.14 for π. Divide each side by 3.14. 135 = d Simplify.
Find the circumference of the circle. Use 3.14 or for π. Explain your choice of π. 1. 22 7 Use for π because 28 is divisible by 7. 227 The circumference is about 176 mi. ANSWER for Examples 1, 2, and 3 GUIDED PRACTICE
Find the circumference of the circle. Use 3.14 or for π. Explain your choice of π. 2. 22 7 The circumference is about 59.66 m. ANSWER Use 3.14 for π because 9.5 is not divisible by 7. for Examples 1, 2, and 3 GUIDED PRACTICE
Find the circumference of the circle. Use 3.14 or for π. Explain your choice of π. 3. 22 7 Use 3.14 for π because 16 is not divisible by 7. The circumference is about 50.24cm. ANSWER for Examples 1, 2, and 3 GUIDED PRACTICE
The circumference is about 100.48cm. ANSWER Use 3.14 forπ because 32 is not divisible by 7. for Examples 1, 2, and 3 GUIDED PRACTICE 4.diameter= 32 in.
22 Use for π because 140 is divisible by 7. 7 The circumference is about 440 ft. ANSWER for Examples 1, 2, and 3 GUIDED PRACTICE 5.diameter= 140 ft.
The circumference is about 9.42cm. ANSWER Use 3.14 forπ because 1.5 is not divisible by 7. for Examples 1, 2, and 3 GUIDED PRACTICE 6.radius= 1.5km
ANSWER The diameter is about 147 feet. for Examples 1, 2, and 3 GUIDED PRACTICE 7.What If? In Example 3, suppose the circumference of the Ferris wheel is 462 feet. What is the diameter of the Ferris wheel?