Answer:
AC is four times longer than DF
Step-by-step explanation:
AC is the diameter of the circle E and DE is the radius of the circle E
AC = 2 x DE
DE is the diameter of the circle F and DF is the radius of the circle F
DE = 2 x DF
AC = 2 x DE
AC = 2 x (2 x DF)
AC = 4 x DF
So AC is four times longer than DF
