Answer:
r = 4.2 cm
d = 8.4 cm
Explanation:
The radius is given. It is line from the middle of the circle to the outer edge of the circle
r = 4.2 cm
The diameter is from the outer edge of the circle, passing through the center, to the opposite outer edge ( and it is a straight line)
It is 2 times the radius
d = 2r = 2 * 4.2 = 8.4 cm