What is the relationship between the center of any circle and the point that lie on the circle?

The distance between the center and any point on the circle is the radius. That's likely what your book or teacher is asking for. 

Note: double the radius and you get the diameter

At a constant it will take one hour to travel 32 mi.at that speed it will take 1/2 hr to travel the remaining 16 mi.it will take 1+1/2 hr to travel the 48mi @ 32mph.so 1 hr = 60 min& 1/2 hr = 30 min1+1/2 hr = 90 min.there are 60s in each 90 × 60 = 3600 seconds.the real question seriously is he why are they driving so slow? ! lol.