Projections of Planes
THEORY: Plane surface (plane/lamina/plate)
A plane is a 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 irregular. Regular plane surfaces are in which all the sides are equal. Irregular plane surfaces are in which the lengths of the sides are unequal.
The positioning of a Plane surface
The three principal planes are vertical, horizontal and profile planes. A plane surface can be oriented in space relative to these three planes in any of the following ways:
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, 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.