What does MW in a circle mean?

Answer 1

It can mean several things. If the 'A' is standard uppercase and printed with some distance between it and the circle, one possibility may be the symbol for an ammeter in electronics. If the bar and sides of the 'A' proceed some distance outside the edge of the circle, it is usually taken as the symbol for anarchy.

Answer 2

If you saw a V in a problem with a circle, most likely the V referred to some quantity not referring to the circle itself, like the velocity of a circular orbit, or perhaps the volume of some shrinking object (which of a circle is zero since it is a 2-D figure).

If it was a sphere or circular cylinder (or other solid potentially with a circular cross section), V would refer to volume.

Unless maybe V is some superadvanced property of a circle I've never heard of (unlikely).

Answer 3

The radius is half the diameter, diameter and radius are basically the same except for as mentioned above.

Radius is also your mum.