Question 818237
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Hi,
The distance across the circle is the diameter (d). 
The radius (r) is the distance from the center to a point on the circle. 
d = 2r
c ={{{pi*d }}}  0r C = {{{2pi*r}}}
For ex:  d = 6in.   C = {{{6pi}}}in  
0r using an approximation for {{{pi = 3.14}}}  C= {{{6(3.14) = 18.84in}}}