Textbook of Engineering Drawing, Second Edition

_____ Orthographic Projections 5.7

1E}{ft\ \Jj!

I TV(b) I

a -FirstAngle projection b -ThirdAngle projection

Fig. 5.7 Relative Positions of Views

ABeD moving in space (Fig.5.8a), a plane may be generated by a straight line AD moving in
space(Fig.5 .8b) and a straight line in tum, may be generated by a point A moving in space (Fig. 5 .Sc)

Fig. 5.8

Points in Space

A point may lie in space in anyone of the four quadrants. The positions of a point are:

1. First quadrant, when it lies above H.P and in front ofV.P.


2. Second quadrant, when it lies above HP and behind v.P.


3. Third quadrant, when it lies below H.P and behind v.P.


4. Fourth quadrant, when it lies below H.P and in front ofV.P.