Answer:
6
Step-by-step explanation:
A = pi r^2
C = 2 pi r
A = B (area)
3C = B
sub C = 2 pi r into 3C = B, and A = pi r ^ 2 into B
3 (2 pi r) = pi r ^ 2
6 pi r = pi r^2
( divide both sides by pi )
6r = r^2
r^2 - 6r = 0
r(r-6) = 0
r = 0 or r-6 = 0
radius can not be 0 , therefore r = 6
hope this makes sense, might be little confusing sorry!
