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.