PROJECTIONS OF A LINE QUESTION ANSWERS CLASS NOTES

PROJECTIONS OF A LINE

QUESTION ANSWERS CLASS

NOTES

Question answers are very important.

These increase the depth of understanding

& clarity. Then fundamentals are easily

applied in real life. Obtain straight line

from two points. A straight line can have

numerous positions in space. Planes form

from straight lines. Use first angle

projection.

Seen from top, drawn at the bottom

 

Fig. (1) Projections of a line parallel to both VP & HP

(2) Projections of a line inclined to HP & parallel to VP

(3) Projections of a line inclined to VP & parallel to HP

(4) Projections of a line inclined to HP & VP

Q What is the final aim of projections of a line?

From line, projection of a plane is

obtained, Final aim is projection of solids.

Q. Define a line in general. Also define it from the drawing point of view.

(i) A line is the shortest distance between two points.

(ii) A line is defined in drawing as

  1. By true length and location of its two ends with respect to the principal planes of projections

  2. Distance between their projectors and location of its two ends with respect to the principal planes

  3. True length, position of one end & its inclination given with one of the principal plane

Q. Define the trace of a line. What are various types of the trace of a line?

Trace of a line is a point where the line meets HP or VP if produced.

Types of trace of a line

Horizontal trace (H.T.) When the line when produced meets at some point to HP.

Vertical trace (V.T.) When the line when produced meets at some point to VP.

NOTE: When a line lies in a plane (HP or VP) its trace is a line. It is the line itself.

Q. Methods to find the true length and true inclinations of a line.

Various methods to find the true length and inclinations are:

  1. Rotation method

  2. Trapezoidal method

  3. Auxiliary plane method

Q. What are the positions of a line with respect to HP and VP?

(a)  Line parallel to both HP and VP

(b) Line inclined to one plane and parallel to the other plane

© Line inclined to both HP and VP

Q. Write some important observations regarding projections of a straight line.

(i) Projection on a plane will be the true length to which plane line is parallel.

(ii) Projection on the plane to which line is inclined is less than the true length. If the line is inclined to HP, its top view is shorter.

(iii)Projection will be a point on the plane to which line is perpendicular.

Q. What is the most important type of problems on the projections of a straight line?

There are two main types of problems on the projections of a straight line.

(a) The projections of a line are given.

Find its true length and true inclinations with HP and VP.

(b) The true length and its true inclinations with HP and VP are given.

Draw the projections.

 

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