Consider the circle.

(4 points)
7th Grade Math Formula Sheet

Use 3.14 for π
and do not round each answer.

Diameter =
feet

Circumference =
feet

Radius =
feet

Area =
square feet

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1 answer

To find the diameter, radius, circumference, and area of a circle, you can use the following formulas:

  1. Diameter (d): The diameter is twice the radius. \[ d = 2r \]

  2. Circumference (C): The circumference can be calculated using the formula: \[ C = \pi d \] or, since \(d = 2r\), \[ C = 2\pi r \]

  3. Radius (r): The radius is half the diameter. \[ r = \frac{d}{2} \]

  4. Area (A): The area of the circle can be calculated using the formula: \[ A = \pi r^2 \]

Example Calculations

Let's say we have a circle where the diameter is given as a certain number of feet. We'll use "d" for values:

  • Diameter (d): If the diameter is provided (e.g., 10 feet), we can directly write: \[ d = 10 \text{ feet} \]

  • Radius (r): \[ r = \frac{d}{2} = \frac{10}{2} = 5 \text{ feet} \]

  • Circumference (C): \[ C = \pi d = 3.14 \times 10 = 31.4 \text{ feet} \]

  • Area (A): \[ A = \pi r^2 = 3.14 \times (5^2) = 3.14 \times 25 = 78.5 \text{ square feet} \]

Summary (using an example of a diameter of 10 feet):

  • Diameter = 10 feet
  • Circumference = 31.4 feet
  • Radius = 5 feet
  • Area = 78.5 square feet

If you want to specify a different diameter for calculations, please provide that value!