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