Cone Set
A set X is called a "cone" with vertex at the origin if for any x in X and any scalar a>=0, ax in X.
See also
Cone, Convex ConeExplore with Wolfram|Alpha
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Cite this as:
Weisstein, Eric W. "Cone Set." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/ConeSet.html