What does it mean when you have a dark circle around your mouth and how to get rid of that?
It usually indicate a familial gastrointestinal syndrome.Consult your doctor,this may be serious than just a cosmetic proble. Or means that you lick arround your mouth to much .
You would do yourself a good deed by calling your eye doctor. Not sure if you mean you see a halo looking circle or dark small spot that moves when you look at a white background. It's probably floaters if it seems to move around when you try to look at it. They say you shouldn't try to focus on it.
If you mean the diameter of a circle with area pi, then the diameter is 2. If you mean the diameter of a circle with circumference pi, then the diameter is 2. If you mean the diameter of a circle with diameter pi, then the diameter is pi. If you mean the diameter of a circle with radius pi, then the diameter is 2pi.
I'm not sure what you mean by "length" of a circle. I'm going to take a wild guess and assume you mean the distance around the circle. The circumference of a circle (distance around it) is (pi) x (diameter). If the diameter is 16 centimeters, then the circumference is 16 pi = 50.2655 centimeters. (rounded)