Coplanar

Points or lines are said to be coplanar if they lie in the same plane.

Example 1:

The points P , Q , and R lie in the same plane A.

They are coplanar.

Example 2:

The points P , Q and R lie in the plane A and the point S lies on the plane B .

They are non coplanar.

Example 3:

The two lines PQ and RS lie in the same plane A .

They are coplanar.

Example 4:

The two lines PQ and UV are skew lines.

They are non coplanar.