1. Engineering Graphics 2018-19-I
Lecture 17
TA101A
Engineering Graphics I By
Dr. Mukesh Sharma
Professor
DEPARTMENT OF CIVIL ENGINEERING
INDIAN INSTITUTE OF TECHNOLOGY KANPUR
KANPUR , INDIA

2. True Shape of Plane through EV and Auxiliary Plane
SA1 A A 1 S 2 H S A2 A1 EV XH F R X A1 , R H A1 X P A2 TS H H R F A2 P S A1 F P A2 XF TL P F RF

3. True Shape of Plane through EV and Method of Rotation1 RH XH
XA1, RA1 PH H
P‘A1 F P A1
SF’ SF XF P TS F
Lines are parallel to hinge line
PF’ R F
True Shape of Plane through EV and Method of Rotation

4. 2H TL 3H 4H 3B H 3F IH 3A F 2F 4F 2B H TS A IF IA IB

5. CH dH aH bH aF bF cF dF H F
Are the lines parallel?

6. aH cH bH dH H F F P aP bP cP dP cF bF dF aF
Are the lines parallel?

7. Conditions for lines to be parallel
- Lines appear parallel in all views
If oblique lines appear parallel in two adjacent views; they are necessarily parallel (no need to see third view)

8. Test for Perpendicularity
gHhH H F eH fH TL eF fF
900 B gF hF C iH jH kH lH iF jF kF lF
900
aHbH H F cH dH cF dF aF bF TL
900 A
Are the lines perpendicular?
condition: at least one of the lines should be in TL and make 900 angle with other line.
If none of the lines is in TL and show 900 angle between them, they are not perpendicular

9. Test for intersection cH cH bH bH aH aH dH dH H H cF F aF F bF aF dF cF dF bF B A
Conclusion – point of intersection of two lines must stay aligned in all views

10. aH bH 1H 2H 3H 4H H F aF bF 1F 2F 3F 4F XH YH YF XF
A Line in a plane – if a line is in the plane, all points of intersection should stay aligned in all views

11. Construct a line parallel to a planebH 1H dH cH aH 2H H F aF dF 2F cF bF 1F
Line 1-2 in top view and Point 1F is given
See we forced the line 1-2 to be parallel to line b-d in front view
As a result, line 1-2 is parallel to the given plane (abc)

12. A line perpendicular to a plane
Very useful in finding shortest distance from a point to a plane pH 1H 2H 3H 4H H F oH oF pF TL EV
4F3F
1F2F
900
A line is perpendicular to plane when the line is in true length at a 900
angle to an edge view of the plane. Line OP is perpendicular to plane
How to draw a perpendicular from a point with this concept?

13. Draw a perpendicular to a plane from point – Recall edge view of plane and perpendicular at 900 needed
PARALLEL OH 2H TL OA 3H TL
3A2A pH 1H PA
900 H A d 4H EV H
4A1A F d 2F 3F pF
Get the edge of plane
See if any line in TL on the plane
See through the line and project all points
Line 2-3 in top view in TL in
In aux view take distance from Front and locate points
Draw a perpendicular from OA on EV ~ OA PA (in TL?)
Project PA to Top view (see the arrows)
Project PH to Front view see PF 1F 4F OF