volume_mute

Find the Radius Then the Circumference

publish date: 2026/05/17 03:18:34.880553 UTC

volume_mute

A circle has a diameter of 20 cm. First find the radius, then find the circumference. Give the approximation using \(\pi \approx 3.14\).

C ≈ 31.4 cm

C ≈ 62.8 cm

C ≈ 125.6 cm

C ≈ 314 cm

C ≈ 62.8 cm

Step 1 — Find the radius: \(r = \dfrac{D}{2} = \dfrac{20}{2} = 10\) cm.

Step 2 — Apply the formula:

\[C = 2\pi r = 2\pi(10) = 20\pi \approx 20(3.14) = 62.8 \text{ cm}\]

Alternatively: \(C = \pi D = \pi(20) = 20\pi \approx 62.8\) cm directly.

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