If the diameter of a circle is $18\text{ cm}$, what is its radius?

Step-by-step solution

1. Step 1: Recall that the radius is half of the diameter: $r=\frac{d}{2}$.
2. Step 2: Substitute $d=18$ cm: $r=\frac{18}{2}=9$.
3. Step 3: The radius is $9$ cm.

Concept tested: Diameter–radius relationship

Published 1 October 2026 · How this solution was prepared and checked