Question

A line of length 20 cm at first lied on the profile plane parallel to the vertical plane and then keeping one of its ends fixed turned 40 degrees with respect to vertical plane and then turned 20 degrees with respect to profile plane. What is the length of the line in side view?

(a) 18.79 cm

(b) 6.8 cm

(c) 12.85 cm

(d) 15.32 cm

I had been asked this question by my school teacher while I was bunking the class.

I need to ask this question from Projection of Line Inclined to both the Planes topic in chapter Projection of Lines of Engineering Drawing

Answer 1

The correct choice is (a) 18.79 cm

To explain I would say: First imagine the line in profile plane parallel to vertical plane as here we are asked to find the side view’s length so even if the line is rotated within the profile plane the line length will not change and also rotated with respect to the profile plane which is calculated as follows 20 x cos (20) = 18.79 cm.