This document discusses projections of oblique lines. It defines an oblique line as one that is inclined to both the horizontal and vertical planes. Both the plan and elevation views of an oblique line will be shorter than the true length. The document provides steps for solving oblique line problems, which involve first assuming the line is parallel to the planes before making inclinations. It then presents an example problem of drawing the projections of a 100mm line inclined at 40° to the horizontal plane and 30° to the vertical plane, with one end positioned in the first quadrant.

1. Unit No:03
Projections of Points & Lines
Yash B. Parikh
M.Tech. (CIM)
Assistant Professor
Department of Mechanical Engineering
Symbiosis Institute of Technology

2. 2
Lines inclined to both Reference Planes
Oblique Lines:
 When the line is inclined to both the reference planes (i.e. H.P. &
V.P.) then that line is called the oblique line.
 Here P.L. & E.L both will be shorter than T.L.
 They will be inclined at apparent angles to XY reference line.
Where,
α > θ
β > Φ
Prof. Yash Parikh

3. 3
Steps to solve Oblique Line Problems
Stage 1 : Assume line parallel to both H.P. & V.P.
Stage 2 : make inclination of the line with first reference plane,
keeping it parallel to the second reference plane.
Stage 3: make inclination of the line with second reference plane,
keeping it parallel to the first reference plane
Prof. Yash Parikh

4. 4
Problem on Oblique Line
Question 1 :
A line AB is 100 mm long. It is inclined at 40˚ to H.P. & 30˚ to
V.P. The end A is 10 mm above H.P. and 25 mm in front of V.P.
Assuming end B is in first quadrant, draw the projections of the
line AB.
Prof. Yash Parikh

5. 5
Thank You
Prof. Yash Parikh