It can stand for many things. One possibility is the vertical axis in solid (3-dimensional) analytical geometry.
For example, learn K-theory:
The A stands for angle.
Side, side, side
Geometry is shapes stand me corrected think what if we had no shape we would not be alive. - Smart 11 year old
How about a kite which is a 4 sided quadrilateral.
Chromium
cannot be determined
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For example, learn K-theory:
what does K stand for in K( , K 12 and K 14 pipes and fittings
The A stands for angle.
to measure; the act of measuring
Alternate interior angles
Side, side, side
Discrete Algebra and Geometry.
noncoplaner
I had a geometry test and its was full with math problems that were very easy for me to under stand.