No, they always are From Wikipedia.org, "The World's Encyclopedia" when I searched coplanar In geometry, a set of points in space is coplanar if the points all lie in the same geometric plane. For example, three distinct points are always coplanar; but four points in space are usually not coplanar. Since 3 points are always coplanar. A point and line are always coplanar
In Euclidean geometry, if and only if they are parallel.
Two are enough, if not coplanar.
Not sure about complanar. Coplanar lines can be collinear but need not be.
They're concentric circles. But I don't think they even need to be coplanar in order to be concentric.
Coplanar means on the same plane. As co-linear means on the same line.
Coplanar means existing on the same plane. It is used in geometry to refer to points or shapes that all exist on one geometric plane.
In Euclidean plane geometry every triangle MUST BE coplanar.
They are always coplanar in Euclidean geometry.
Non-coplanar simply means not on the same plane (referring to points on a plane; geometry)
Yes, in Euclidean geometry.
CorrectParallel lines as well as intersecting lines must be coplanar (in Euclidean geometry not quite sure about hyperbolic geometry...).Lines in space which neither are coplanar nor intersecting are called "skew"
They need not be. The four vertices of a quadrilateral are coplanar but NOT collinear. On the other hand, any line (in Eucledian geometry) has an infinite number of points on it - all of which are coplanar.
In Euclidean geometry, parallel line are alwayscoplanar.
No, they always are From Wikipedia.org, "The World's Encyclopedia" when I searched coplanar In geometry, a set of points in space is coplanar if the points all lie in the same geometric plane. For example, three distinct points are always coplanar; but four points in space are usually not coplanar. Since 3 points are always coplanar. A point and line are always coplanar
Non coplanar lines.
In Euclidian geometry it's a point. In non-Euclidean geometry all bets are off.