ok
relation of diameter to radius
2 radius=1diameter
radius=1/2 diameter
2r=d
d/2=r
circumfernce=2pir
since 2r=d
circumference=2d
so
c=pid=2pir
so if ou have circunference and you want to find diameter and radius
c=pid
divde both sides by pi
c/pi=d
c=2pir
divide both sides by 2pi
c/(2pi)=r
so
r=c/(2pi)
d=c/pi
