Question

what is the diameter of this circle?

Explanation:

Step1: Identify radius from graph

Count the grid - squares from the center of the circle at $(0, - 8)$ to the edge of the circle. The radius $r$ is 2 units.

Step2: Use diameter - radius relationship

The formula for the diameter $d$ of a circle is $d = 2r$. Substitute $r = 2$ into the formula. So $d=2\times2$.

Answer:

4