The formula for finding out the circumference of a circle is:

Circumference = 2(pi x r)

Where r is the radius.

Now, the value of pi is always taken as 3.14. If we have the value of the circumference, we can find the value of the radius.

Let's suppose that the circumference is x. Therefore, to find the radius:

C = 2(Pi.r)

x = 2(3.14.r)

x = 6.28 (2r)

x = 12.56r

r = x/12.56

Now the diameter is always twice the length of the radius. Therefore, any answer that you get for the radius, you just have to multiply it by 2 to obtain the value for the diameter.

In this case:

Diameter = 2xr

Diameter = 2(x/12.56)

Let's do this with an actual number. Supposing the circumference is 20cm, the radius would be:

20 = 2 (Pi.r)

20 = 2 (3.14r)

20 = 6.28r

r = 20/6.28

r = 3.19 cm

Diameter = 2r

Diameter = 3.19 x 2

= 6.38 cm

Circumference = 2(pi x r)

Where r is the radius.

Now, the value of pi is always taken as 3.14. If we have the value of the circumference, we can find the value of the radius.

Let's suppose that the circumference is x. Therefore, to find the radius:

C = 2(Pi.r)

x = 2(3.14.r)

x = 6.28 (2r)

x = 12.56r

r = x/12.56

Now the diameter is always twice the length of the radius. Therefore, any answer that you get for the radius, you just have to multiply it by 2 to obtain the value for the diameter.

In this case:

Diameter = 2xr

Diameter = 2(x/12.56)

Let's do this with an actual number. Supposing the circumference is 20cm, the radius would be:

20 = 2 (Pi.r)

20 = 2 (3.14r)

20 = 6.28r

r = 20/6.28

r = 3.19 cm

Diameter = 2r

Diameter = 3.19 x 2

= 6.38 cm