Formula for calculating diameter?????

[wind_rose_2]

Age has been definately taking its toll on me lately....l am fabricating a simple sea bag/ duffle bag and have forgotten how to calculate the diameter required for the bottom of the bag..it is , of coarse ..round and will need allowance for sewing to the sides of the bag..the bag walls are completed and when laid flat measure 18 3/4 inches which means the perimeter would be 37 1/2 inches...do l have to multiply 37.5x3.14 to arrive at the diameter?????
LOST IN MY MIND>>>CAN"T FIGUE A WAY OUT!  ???

Dave

[PDQ]

http://math.about.com/library/blcirclecalculator.htm

:D

[fragged8]

try this I made .
you need Adobe Acrobat to open it

not sure how long the link will last
https://snuggtopz.sharefile.com/f/fodec8cf-c95a-4add-b4f6-3ff96e750a2c


let me know how it works for you.

Rich

[Joys Shop]

Found on the internet
   
If you know the radius, then the diameter is 2R.
If you know circumference, then the diameter is C/(pi).
If you know the area, then the diameter is the square root of 4A/(pi).

R is the radius of a circle,
C is the circumference and
A is the area

[wind_rose_2]

Done!..Just a brain fart..thanks guys!
Dave