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Circumference & Area of Circles Quick Check
2 of 52 of 5 Items
Question
Which of the following uses the correct formula to find the approximate circumference of a circle that has a radius of 450?(1 point)
Responses

C≈3.14⋅450÷2
upper C approximately equals 3.14 times 450 divided by 2

C≈3.14⋅150
upper C approximately equals 3.14 times 150

C≈3.14⋅4502
upper C approximately equals 3.14 times 450 squared

C≈2⋅3.14⋅450
upper C approximately equals 2 times 3.14 times 450

page 20 of 20
Circumference & Area of Circles Quick Check
3 of 53 of 5 Items
Question
Which formula correctly describes the proportional relationship between the circumference of a circle and the diameter?(1 point)
Responses

π=dC
pi equals Start Fraction d over upper C

A=πr2
upper A equals pi r squared

Cd=π
Start Fraction upper C over d End Fraction equals pi

C=πd
upper C equals Start Fraction pi over d End Fraction

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Circumference & Area of Circles Quick Check
4 of 54 of 5 Items
Question
Use the correct formula to find the area of a circle if the diameter is 21 mi. Round to the nearest hundredths place. Use 3.14 for π .(1 point)
Responses

346.19 mi.2
346.19 mi squared

65.94 mi.2
65.94 mi squared

131.88 mi.2
131.88 mi squared

1,384.74 mi.2
1,384.74 mi squared

page 20 of 20
Circumference & Area of Circles Quick Check
5 of 55 of 5 Items
Question
Which of the following is the correct formula for finding the area of a circle?(1 point)
Responses

A=2πr
upper A equals 2 pi r

A=C2÷4πA=πd2
upper A equals upper C squared divided by 4 pi upper A equals pi d squared

A=πd
upper A equals pi d

A=πr2
upper A equals pi r squared
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1 answer

Here are the answers to the questions based on the information provided:

Question 1: Which of the following uses the correct formula to find the approximate circumference of a circle that has a radius of 450?

  • Response: C ≈ 2⋅3.14⋅450
    This is the correct formula for circumference (C = 2πr) where r is the radius.

Question 2: Which formula correctly describes the proportional relationship between the circumference of a circle and the diameter?

  • Response: C = πd
    This is the correct formula for explaining the relationship between circumference (C) and diameter (d).

Question 3: Use the correct formula to find the area of a circle if the diameter is 21 mi. Round to the nearest hundredths place. Use 3.14 for π.

  • First, find the radius. The radius r = diameter / 2 = 21 / 2 = 10.5 mi.
  • Use the formula for the area of a circle: A = πr² = 3.14 * (10.5)²
  • A = 3.14 * 110.25 = 346.19 mi².
  • Response: 346.19 mi²

Question 4: Which of the following is the correct formula for finding the area of a circle?

  • Response: A = πr²
    This is the correct formula for the area of a circle.

All the responses are now aligned with the questions and provide the correct answers.