If the diameter of a circle changes from 18 cm to 6 cm, how will the circumference change?
A) multiplies by 1/3
B) multiplies by 3
C) increases by 10
D) decreases by 10

Respuesta :

we know that 

the length of a circumference=2*pi*r
for D1=18 cm--------------> r1=9cm
L1=2pi*9-------> 18pi cm

for D2=6 cm-----------> r2=3 cm
L2=2pi*3-------> 6pi cm

L2/L1----------> (6pi)/(18pi)---->1/3

the answer is the option A) multiplies by 1/3