Diameter
n
geometry, a diameter of a
circle is any straight
line segment that passes through the center and whose endpoints are on the circular boundary, or, in more modern usage, the length of such a line segment. When using the word in the more modern sense, one speaks of
the diameter rather than
a diameter, because all diameters of a
circle have the same length. This length is twice the radius. The diameter of a circle is also the longest chord that the circle has.
The diameter of a connected graph is the distance between the two vertices which are furthest from each other.
Encyclopedia
In
geometry, a
diameter of a
circle is any straight
line segment that passes through the center and whose endpoints are on the circular boundary, or, in more modern usage, the length of such a line segment. When using the word in the more modern sense, one speaks of
the diameter rather than
a diameter, because all diameters of a
circle have the same length. This length is twice the radius. The diameter of a circle is also the longest chord that the circle has.
The
diameter of a connected graph is the distance between the two vertices which are furthest from each other. The distance between two vertices
a and
b is the length of the shortest path connecting them .
The two definitions given above are special cases of a more general definition. The
diameter of a
subset of a metric space is the least upper bound of the distances between pairs of points in the subset. So, if
A is the subset, the diameter is
- sup .
In medical parlance the diameter of a lesion is the longest line segment whose endpoints are within the lesion.
Diameter symbol
The
symbol or variable for diameter is similar in size and design to ø, the lowercase letter o with stroke.
Unicode provides character number 8960 for the symbol, which can be encoded in
HTML webpages as
⌀ or
⌀. Proper display of this character, however, is unlikely in most situations, as most
fonts do not have it included. ' In most situations the letter ø is acceptable, obtained in
Microsoft Windows by holding the
[Alt] key down while entering
0 2 4 8 on the
numeric keypad.
It is important not to confuse a diameter symbol with the empty set symbol, similar to the uppercase Ø. Diameter is also sometimes called phi , although this seems to come from the fact that Ø and ø look like F and f, the letter phi in the
Greek alphabet.
See also
External links
