Circumference c=2*3. 14*r

r/c = 1/(2 * 3. 14)& lt； 1/3

2. Comparison of circumference and diameter of a circle

Diameter d=2*r

Obviously 2 * 3.14 * r >; 2*r (the condition of this inequality is r >；; 0, and the radius must be greater than 0)

Therefore, c>d.