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What is the approximate circumference of a circle that has a radius of 63? Use 3.14 for π

and express your answer to the hundredths place.(1 point)
a
What is the approximate circumference of a circle that has a diameter of 20? Use 3.14 for π
and express your answer to the tenths place.(1 point)
A circle has an approximate circumference of 574 meters
. What is the circle’s diameter, rounded to the nearest tenth? Use 3.14
for π
. (1 point)
meters

If a circle has a radius of 38 inches
, what is its approximate circumference to the nearest hundredths? Use 3.14
for π
.(1 point)
inches
The radius of a circle is 75 mm. What is the approximate area of the circle? Write your answer to the tenths place. Use 3.14 for π
.(1 point)
mm2

1 answer

To solve the problems, we can use the formulas for circumference and area of a circle:

  1. Circumference of a Circle

    • Circumference (C) = 2πr or C = πd (where r is the radius and d is the diameter)

  2. Area of a Circle

    • Area (A) = πr²

Now let's solve each question step by step:

1. Circumference of a circle with a radius of 63

Using the formula \( C = 2\pi r \): \[ C = 2 \times 3.14 \times 63 = 6.28 \times 63 = 395.64 \] Answer: The approximate circumference is 395.64.

2. Circumference of a circle with a diameter of 20

Using the formula \( C = \pi d \): \[ C = 3.14 \times 20 = 62.8 \] Answer: The approximate circumference is 62.8.

3. Diameter of a circle with a circumference of 574 meters

Using the formula \( C = \pi d \): \[ d = \frac{C}{\pi} = \frac{574}{3.14} \approx 182.5 \] Answer: The diameter is approximately 182.5 meters.

4. Circumference of a circle with a radius of 38 inches

Using the formula \( C = 2\pi r \): \[ C = 2 \times 3.14 \times 38 = 6.28 \times 38 \approx 238.64 \] Answer: The approximate circumference is 238.64 inches.

5. Area of a circle with a radius of 75 mm

Using the formula \( A = \pi r^2 \): \[ A = 3.14 \times (75^2) = 3.14 \times 5625 = 17662.5 \] Answer: The approximate area is 17662.5 mm².

In summary:

  1. Circumference with radius 63: 395.64
  2. Circumference with diameter 20: 62.8
  3. Diameter from circumference 574 m: 182.5 m
  4. Circumference with radius 38 in: 238.64
  5. Area with radius 75 mm: 17662.5 mm²