What is the formula to get the diameter when circumference is given I didn't understand it - Maths - The Circle

Question

What is the formula to get the diameter when circumference is
given? I didn't understand it

Neha Sethi · Accepted Answer

Let r be the radius of circleWhen circumferenceC  of circle is given and we know that C=2πrFrom here we can calculate r and we know that diameter d=2rExample:  Circumference of circle is 40⇒40=2πrTaking π=3
14⇒r=402π=20π=203 14=6
37So, diameter d=2r=2×6 37=12 74 units

What is the formula to get the diameter when circumference is given? I didn't understand it.