Question

what is the diameter of this circle?

Explanation:

Step1: Identify radius length

Count the grid - squares from the center of the circle (at the origin $(0,0)$) to the edge of the circle. The radius $r$ is 5 units.

Step2: Use diameter - radius relation

The formula for the diameter $d$ of a circle is $d = 2r$. Substitute $r = 5$ into the formula.
$d=2\times5$

Answer:

10