Answer:
Radius: 9 cm
Diameter: 18 cm
Explanation:
Remember that the Diameter is the measure of the space going across the circle as shown as the line inside the circle
The Radius is the measure of the space from the center to the circle to the edge of the circle, in other words, the radius is always going to be half of the diameter
For example, if the diameter for a plate is 20 inches, then my radius is going to be half of that, so 20 divided in half is 10 inches