Assertion: coordinate system's angle | /r/CreatedBy | the ray
Facets:
value: to the point
type: OTHER
value: from the origin
type: OTHER
Source sentences:
text: It does not itself have well-defined polar coordinates, because the polar coordinates of a point include the angle made by the positive x-axis and the ray from the origin to the point, and this ray is not well-defined for the origin itself.