Question

A line of length 55 mm lies on profile plane whose ends are at a distance of 15 mm and 20 mm to horizontal plane. What is the length in top view?

(a) 54.77 mm

(b) 5 mm

(c) 0 mm

(d) 35 mm

I had been asked this question in unit test.

This intriguing question comes from Projection of Line Contained by Plane topic in division Projection of Lines of Engineering Drawing

Answer 1

The correct answer is (a) 54.77 mm

The best I can explain: Given the line is of length 55 mm present on profile plane and ends are at 15 and 20 mm away from horizontal plane. As we imagine the projection planes we can get the top view and distance relation as given here √(55^2-(20-15)^2 )=54.77 mm.