Pronounced "co-PLANE-are"

Two objects are coplanar if they both lie in the same plane. In the figure above, the two rectangles ABCD and PQRS are both coplanar. Try dragging them about and you will see they both lie in the yellow plane P.

The blue rectangle however is in a different plane, and is therefore not coplanar with ABCD and PQRS. Drag it around and see that it lies in a plane perpendicular to plane P.

Other line topics

• Point definition
• Line definition
• Vertical lines
• Horizontal lines
• Line segment
• Midpoint of a line
• Ray
• Angle
• Opposite rays
• Intersection
• Parallel lines
• Transversal
• Line bisector
• Perpendicular bisector
• Coplanar
• Collinear points
• Plane