Projections of Planes

Plane surface (plane/lamina/plate)

A plane is as two dimensional surface having length and breadth with negligible thickness. They are formed when any three non-collinear points are joined. Planes are bounded by straight/curved lines and may be either regular or an irregular. Regular plane surface are in which  all the sides are equal. Irregular plane surface  are in which the lengths of the sides are unequal.

Positioning of a Plane surface

A plane surface may be positioned in space with reference to the three principal planes of projection in any of the following positions:

• Parallel to one of the principal planes and perpendicular to the other two.
• Perpendicular to one of the principal planes and inclined to the other two.
• Inclined to all the three principal planes.

Projections of a Plane surface

A plane surface when held parallel to a plane of projection, it will be perpendicular to the other two planes of projection.  The view of the plane surface projected on the plane of projection to which it will be perpendicular will be a line, called the line view of a plane surface. When the plane surface is held with its surface parallel to one of the planes of projection, the view of the plane surface projected on it will be in true shape because all the sides or the edges of the plane surface will be parallel to the plane of projection on which the plane surface is projected.
When a plane surface is inclined to any plane of projection, the view of the plane surface projected on it will be its apparent shape.
A few examples of projections of plane surfaces are illustrated below: