# Engineering Drawing Questions and Answers – Projection of Straight Lines Parallel to Plane

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This set of Engineering Drawing Multiple Choice Questions & Answers (MCQs) focuses on “Projection of Straight Lines Parallel to Plane”.

1. If a line AB parallel to both the horizontal plane and vertical plane then the line AB is _____________
a) parallel to profile plane
b) lies on profile plane
c) perpendicular to profile plane
d) inclined to profile plane

Explanation: For any line if it is parallel to two perpendicular planes then the line will definitely perpendicular to other plane perpendicular to both the previous planes. And whether the line lies on the plane or not depends on conditions given but we can’t just imagine.

2. A line AB of length 20 cm is placed in 1st quadrant and parallel to profile plane and the end A and B are 15, 10 cm away from the horizontal plane respectively. The length of the line in the top view is ______ cm.
a) 11.18
b) 13.2
c) 17.32
d) 19.36

Explanation: The distance between the projectors drawn from A and B to horizontal plane gives the length of line in top view given the line parallel to profile plane. The difference in distances from A and B to horizontal plane is 5 (15-10). Given length is 20 cm so required length is √(〖20〗^2-5^2 )= 19.36 cm.

3. A line of length 15 cm is parallel to horizontal plane and makes an angle of 30 degrees with vertical plane. The length of line in top view is ____ cm.
a) 30
b) 15
c) 12.9
d) 7.5

Explanation: Given the line is parallel to horizontal plane and makes an angle of 30 degrees with vertical plane. The top view gives the actual length of the line because the top view is always the projection of objects on horizontal plane to which the line is parallel.

4. A line AB of length 10 cm is placed in 2nd quadrant parallel to vertical plane and 5 cm away from the vertical plane and ends are 7 cm and 4 cm from horizontal plane. The top view and front view lines apart from each other.
a) True
b) False

Explanation: Accordingly the given distances and length if the projections are drawn the front view and top view intersect with each other as for 2nd quadrant the projections of a front view and top view overlaps.

5. A line of length 16 cm is parallel to horizontal plane and makes an angle of 30 degrees with vertical plane placed in 3rd quadrant. The length of line in front view is ____ cm.
a) 32
b) 16
c) 13.8
d) 8

Explanation: The line given is parallel to horizontal plane and makes an angle of 30 degrees with vertical plane so the length of line front view will be cosine (30)x actual length of line =13.8 cm. There will be no difference the line is in any quadrant.

6. A line AB of length 15 cm is placed in 4th quadrant and parallel to profile plane and the end A and B are 8, 6 cm away from the horizontal plane respectively. The length of the line in front view is ______ cm.
a) 14.8
b) 9
c) 7
d) 2

Explanation: The difference in distances from A and B to horizontal plane is 2 (8-6) cm. And this front view of line in orthographic projection is perpendicular to the reference line as the line in projection planes is parallel to profile plane.

7. A line AB of length 2 m is placed in 2nd quadrant and parallel to vertical plane and the end A and B are 0.5 m and 0.3 m away from the horizontal plane respectively. The length of the line in top view is ______ m.
a) 1.98
b) 1.97
c) 1.936
d) 2

Explanation: The distance between the projectors drawn from A and B to horizontal plane gives the length of line in top view given the line parallel to vertical plane. The difference in distances from A and B to horizontal plane is 0.2 (0.5-0.3). Given length is 2 m so required length is √(22-0.22 )= 1.98m.

8. A line of length 30 inches is parallel to profile plane and makes an angle of 60 degrees with vertical plane. The length of line in top view is ____ inches.
a) 30
b) 15
c) 25.9
d) 51.9

Explanation: Given the line is parallel to profile plane and makes 60 degrees with vertical plane. There will be no need for distance from profile plane. The length of line from top view will be sin(60) x length of the line= sin(60) x 30 inches =25.9 inches.

9. A line of length 25 cm is parallel to horizontal plane and makes an angle of 45 degrees with profile plane. The length of line in side view is ____ cm.
a) 25
b) 12.5
c) 88.3
d) 17.67

Explanation: Given the line is parallel to profile plane and makes 45 degrees with profile plane. There will be no need for distance from a profile plane. The length of line from top view will be sin (45) x length of the line= sin (45) x 25 cm = 17.67 cm

10. The length of line parallel to one of the plane of projection planes will show same length if view of that line is drawn on to the plane.
a) True
b) False

Explanation: The length of line parallel to one of the plane of projection planes will show same length if view of that line is drawn on to the plane because the projections on the plane to that line are parallel to other planes.

11. A line parallel to horizontal plane and at a distance of 10 units to it and both the end of line are 6 units away from the vertical plane. Which of the following statement is false?
a) The line parallel to vertical plane
b) The side view of line gives a point
c) The length of line in front view is 10 units
d) The length of line in top view is 6 units

Explanation: The line which is equidistance from a plane is said to be parallel to it. The line which is parallel to two perpendicular planes will be perpendicular to other perpendicular plane to the earlier planes.

12. A line AB of length 12 inches is perpendicular to profile plane at distance of 6 inches from vertical plane and 3 inches from horizontal plane. The distance from line to xy reference line in top view is _____ inches.
a) 6
b) 3
c) 12
d) 0

Explanation: Given the line perpendicular to profile plane. Top view gives the length of line and distance from the xy reference line which is the perpendicular distance from the line to vertical plane. It is given in question as 6 inches.

13. A line AB of length 3 m is perpendicular to vertical plane at distance of 2 m from profile plane and 0.5 m from horizontal plane. The distance from line to xy reference line in front view is _____ m.
a) 1.5
b) 0.5
c) 2
d) 3

Explanation: Given the line perpendicular to vertical plane. Front view shows as point and distance from the xy reference line and vertical reference line. The distance from horizontal plane is given in question as 0.5 m.

14. A line AB of length 24 cm is parallel to vertical plane and perpendicular to profile plane held at a distance of 5 cm away from horizontal plane and 6 cm away from the vertical plane. The distance from xy reference line to line AB is _____ cm in top view.
a) 6
b) 12
c) 5
d) 7.8

Explanation: Asked for top view, which gives the distance from vertical plane and profile plane because the top view is parallel to horizontal plane. Also given the line is perpendicular to profile plane. the distance from xy reference line to line AB will be 6 cm.

15. A line AB of length 24 cm is parallel to vertical plane and perpendicular to profile plane held at a distance of 5 cm away from horizontal plane and 6 cm away from the vertical plane. The distance from xy reference line to line AB is _____ cm in front view.
a) 6
b) 12
c) 5
d) 7.8

Explanation: Asked for front view, which gives the distance from horizontal plane and profile plane because the front view is parallel to vertical plane. Also given the line is perpendicular to profile plane. the distance from xy reference line to line AB will be 5 cm.

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