Pi (π) Math Example 4

Follow the full solution, then compare it with the other examples linked below.

Example 4

easy
A circle's circumference is C=62.8C = 62.8 cm. What is its diameter? Use π≈3.14\pi \approx 3.14.

Solution

  1. 1
    Step 1: Use C=πdC = \pi d, so d=C/πd = C/\pi.
  2. 2
    Step 2: d=62.8/3.14=20d = 62.8 / 3.14 = 20 cm.

Answer

d=20d = 20 cm
Pi is defined as π=C/d\pi = C/d, so rearranging gives d=C/πd = C/\pi. This is also how π\pi was historically measured — dividing a circle's measured circumference by its measured diameter.

About Pi (π)

The ratio of a circle's circumference to its diameter, approximately 3.14159…3.14159\ldots

Learn more about Pi (π) →

More Pi (π) Examples

Example 1 easy

A circle has a diameter of 10 cm. What is its circumference? Use [formula].

Example 2 medium

A circle has a radius of 7 m. Find its area. Use [formula].

Example 3 medium

A circular pool has a circumference of 31.4 m. Find its radius and area. Use [formula].

Example 5 hard

A wheel of radius 0.5 m rolls without slipping. How many full rotations does it make to travel 100 m

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