Wikipedia:Reference desk/Archives/Mathematics/2023 February 3

= February 3 =

Thickness of an edge
I understand that a circle is the edge of a disc and that this edge can have some "thickness" which is often referred to as "perimeter" or "circumference".

How do mathematicians measure the thickness of this perimeter or circumference? I a computer it can be done with layers of circular pixel dots, but how is it done on the classical way with a pen and paper? 2001:44C8:420D:BCCA:FC4A:9274:819C:4200 (talk) 06:38, 3 February 2023 (UTC)


 * The circumference is the length around the circle, not a “thickness”. Mathematicians do not consider a circle to have any “thickness”. –jacobolus (t) 07:30, 3 February 2023 (UTC)
 * You may be thinking of an annulus. –jacobolus (t) 07:31, 3 February 2023 (UTC)
 * Thank you. I believe that an Annulus is what I meant to. 2001:44C8:420D:BCCA:E801:CCAF:F515:E97D (talk) 08:08, 3 February 2023 (UTC)