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How Do You Find the Area of a Circle if You Know the Diameter?

Find the area of a circle with a diameter of 14 inches. Use 3.14 for π.

Summary

  1. Remember, to find the area of a circle, you need to multiply pi by the radius squared
  2. 'π' is pi, an irrational number with a value of approximately 3.14
  3. 'd' is the diameter, which is 14 inches
  4. We can determine the radius, 'r', by taking half of the diameter
  5. Since our diameter is 14, our radius is 7
  6. So we plugged our known information into the A=πr2 formula
  7. We get "A=153.86", which means the area is 153.86 inches squared!

Notes

    1. Remember, to find the area of a circle, you need to multiply pi by the radius squared:
    2. A = πr2
    1. 'π' is pi, an irrational number with a value of approximately 3.14
    2. 'd' is the diameter, which is 14 inches
    3. We can determine the radius, 'r', by taking half of the diameter
    1. We can determine the radius, 'r', by taking half of the diameter
    2. d = 14
    3. r = 1/2(d) = d/2 = 14/2 = 7
    1. π = 3.14
    2. r = 7
    3. So "A=πr2" becomes "A=(3.14)(7)2"
    1. A = (3.14)(7)2
    2. (7)2 = 49
    3. A = (3.14)(49) = 153.86
    4. We get "A=153.86", which means the area is 153.86 inches squared!