Calculation: 3. 14x20? x 1/4x2-20? =228
228x 1/4=57
3. 14x30? x 1/4x2-30? =5 13
5 13÷4= 128.25
57+ 128.25= 185.25
circumference ratio
The ratio of the circumference to the diameter of a circle is called pi. It is an infinite acyclic decimal, usually represented by the letter π (pronounced "pie").
π ≈ 3. 14159265323846 2643 ... The approximate value is usually 3.14. We can say that the circumference of a circle is π times the diameter, or about 3. 14 times the diameter, but we can't directly say that the circumference of a circle is 3. 14 times the diameter.