1. FRIDAY, APRIL 22 ND WILL BE USED AS THE BUFFER DAY FOR MEL 110 PRACTICALS. -TIME: 9 AM TO 1 PM. -VENUE: WS 204 LAB 13. WILL BE COMPUTER BASED IN THE CAGIL. ANNOUNCEMENTS

2. TV FV    A flag post is held by 3 wires symmetrically placed around it. They are hooked to the post at a height of 12.5 m. and anchored to the ground at a distance of 2m, 2.5m, and 3 m from the pole axis respectively. Draw their projections and find their true lengths and true inclinations with the horizontal by method of rotation. Draw top and front views incorporating given distances. Use method of revolution/rotation to obtain true lengths of the wires. With o as center and oa, ob, oc as radii, rotate the wires so that they are parallel to frontal plane.  , , and  are the true inclinations with the horizontal. 12.5 2 2.5 3 Flag post Ground Wire o c’b’a’ a b c o

3. An oblique square pyramid of side 4 cm and height 5 cm is placed with its base a, b, c, d horizontal with ab making an angle of 30 o to the vertical plane. Draw its projections and find the true lengths and true inclinations with the horizontal plane of its edges ao, bo, co, do meeting at the vertex o. The axis of the pyramid is inclined at 60 o to the horizontal and parallel to the frontal plane. Draw top view of square with one side having angle 30 o with the frontal plane. Find the point of intersection of diagonals of the square. This is the lower point of the pyramid axis. Project this point in the front view and draw the axis from it, at an angle of 60 o to the horizontal up to a vertical height of 5 cm. As the axis is parallel to the frontal plane, it can be projected back into the top view. Find true lengths by rotation method. In this case o has been taken as center and oa, ob, oc, od as radii, rotate the lines in top view to make them parallel to frontal plane. Project true lengths. a’ b’ c’d’ a b c d o o’     c1c1 d1d1 b1b1 a1a1 T F 60 o True lengths 30 o 5 4 f f’

4. Three points A, B, and C represent milestones and are 7.5 m above the ground level, on the ground level, and 9 m below ground level and 9 m below ground level respectively. They are connected with each other by roads and are seen at angles of depression of 10 o, 15 o and 30 o respectively from a point O on a hill 30 m above the ground level. A is due Northeast, B is due North and C is due Southeast of O. Find the lengths of the connecting roads. A B C A’ B’ C’ O O 30 7.5 9 10 o 15 o 30 o T F Obtain true lengths in one view by subtending given angles from pt. O to the respective heights Required distance is True Length of AB + BC + CA HINT: Rotate AB, BC, CA in any one view and obtain True Lengths in the other view. E.g. AC 1 is one such length Add the distances to get the final answer C1C1 N NE SE Ground level

5. To find the piercing point and angle of inclination of a line with a plane p1p1 Line Plane Edge view of the plane Principal line True length of principal line p’ p Part of the line hidden by the plane should be shown dotted T F p2p2 Angle between line and plane True length of line Edge view of plane p3p3 Draw auxiliary views such that you get the TRUE LENGTH of the line and EDGE VIEW of the plane T A1 A2 A1 A2 A3 p, p’, p 1, p 2, p 3 are the piercing point of the line with the plane

6. A B Q P ZY XW S R To find the line of intersection of two planes AB is the line of intersection obtained by getting the piercing point (A) of WZ with plane PQRS and (B) of XY with plane PQRS.

7. A B Q P ZY X W S R To find the line of intersection of two planes AB is the line of intersection. In this case the piercing point of XY with PQRS (B) and of PS with plane WXYZ (A) is to be obtained.

8. To find corresponding points on lines appearing vertical in TV and FV and obtaining True Length a’ b’ c’ a b c d’ d   1. With a’ as center rotate a’d’ and a’b’ and make the line horizontal 2. Project d’ and b’ upto a line that is horizontal and in line with a meeting it at d1 and b1 respectively 3. Join b1 and b. Draw a line parallel to b1b to intersect ab in d d’ b’ b1 d1 e’ e Principle line True length The ratio of corresponding distances in both views should be same T F

9. a’ a b’ b T F Horizontal Trace: Projection of point of intersection of extension of AB with the Top plane Vertical Trace: Projection of point of intersection of extension of AB with the Frontal plane Definition: The point of intersection of a line-produced with a plane is called its TRACE on that plane. VT HT To find the TRACE of a line: Case I VT HT A B H V HV

10. a’ a b’ b T F Horizontal Trace: Projection of point of intersection of extension of AB with the Top plane Vertical Trace: Projection of point of intersection of extension of AB with the Frontal plane Definition: The point of intersection of a line-produced with a plane is called its TRACE on that plane. VT HT To find the TRACE of a line: Case II VT HT A B H V H V

11. a’ a b’ b T F Horizontal Trace: Projection of point of intersection of extension of AB with the Top plane Vertical Trace: Projection of point of intersection of extension of AB with the Frontal plane Definition: The point of intersection of a line-produced with a plane is called its TRACE on that plane. VT HT To find the TRACE of a line: Case III VT HT A B H TL

12. a’ a b’ b T F Horizontal Trace: Projection of point of intersection of extension of AB with the Top plane Vertical Trace: Projection of point of intersection of extension of AB with the Frontal plane Definition: The point of intersection of a line-produced with a plane is called its TRACE on that plane. VT HT To find the TRACE of a line (Trapezoidal method): Case III HT A B TL a b A B

13. A G FE D C B I H A’ H’,G’ I’,F’ B’,E’ C’,D’ 30 o A G FE D C B I H Approach I: Use Frontal plane as the wall Auxiliary view will give edge view and angle with frontal plane Principal line A G FE D C B I H A’ H’,G’ I’,F’ B’,E’ C’,D’ 30 o Approach II: Include a wall at 30 o to the edges DC and GH PAV, in which PAP is the wall Obtain edge view using principal plane concept in SAV. Angle that it makes with the axis is the angle with the wall Q. Two regular pentagonal plates ABCDE and AFGHI of equal sizes (side length 30 mm) are joined at A such that the included angle between them is 75 o. The edges opposite to corner A are on the ground and make 30 o with a vertical wall. a)Draw projections of the plates. b)Find the angle of the plates with the wall. 75 o