How do you find circumference given the radius?

Answer 1

Remember the eqution and comit to memory

C = 2pir

or

C = pi d

Where 'C' is the circumference

'r' is the radius

'd' is the diamter.

and 'pi' is the constant of proportion of circles at 3.141592.... usually approximated to 3.14

e.g. If the radius is 5

Then C = 2 * 3.14 * 5

C = 10*3.14

C = 31.4

Answer 2

To find the circumfrence you would double the radius and multiply it by pi.