Diameter – Harry & Co Jewellery

Definition and Properties of Diameter

A diameter is a straight line segment that passes through the center of a circle or sphere.
It is the longest chord of a circle.
The length of a diameter is twice the length of the radius.
In a convex shape, the diameter is the largest distance between two opposite parallel lines tangent to its boundary.
For an ellipse, a diameter is any chord passing through the center of the ellipse.

The concept of diameter extends beyond circles, spheres, and convex shapes.
It can be defined for any n-dimensional object, such as a hypercube or a set of scattered points.
The diameter of a subset in a metric space is the least upper bound of all distances between pairs of points in the subset.
The diameter of the empty set is either considered as negative infinity or zero, depending on the context.
The diameter of a solid object or set of scattered points is the same as the diameter of its convex hull.

The symbol ⌀ is used in technical drawings or specifications to represent diameter.
It can be used as a prefix or suffix for a number to indicate diameter (e.g., ⌀ 55 mm).
In Windows, the symbol ⌀ can be entered using Alt code 8960.
The symbol ⌀ is not included in the dim.shx font, but it is available in other fonts.
The wasysym package provides support for the symbol ⌀ in LaTeX.

The diameter of a circle is exactly twice its radius.
This relationship holds true only for circles and in the Euclidean metric.
Jungs theorem provides more general inequalities relating the diameter to the radius.
The radius is the distance from the center of a circle to any point on its circumference.
The diameter is the distance between two points on the circumference passing through the center.

Angular diameter refers to how large a sphere or circle appears.
Caliper and micrometer are tools used for measuring diameters.
Conjugate diameters are perpendicular diameters of a circle or hyperbolic-orthogonal diameters of a hyperbola.
Diameter in group theory measures the complexity of a finite group.
Eratosthenes calculated the diameter of the Earth around 240 BC.

Reference	URL
Glossary	https://harryandcojewellery.com.au/blogs/glossary/diameter
Wikipedia	http://en.wikipedia.org/wiki/Diameter
Wikidata	https://www.wikidata.org/wiki/Q37221
Knowledge Graph	https://www.google.com/search?kgmid=/m/0277z