How to find end points of a parallel line?

Question

Heres my scenario.. I have two parallel lines segments,AB and CD of equal length. If A,B are known, how do I find C and D?!

Hagen von Eitzen · Answer 1 · 2013-01-23 07:39:22Z

up vote 2 down vote

$x_3,y_3$ can be arbitrary. Then let $x_4=x_3+x_2-x_1, y_4=y_3+y_2-y_1$.

If you more specifically want $ABDC$ to be a rectangle, select $t$ arbitrary, then let $x_3=x_1+t(y_2-y_1), y_3=y_1+t(x_1-x_2)$ in the above.

answered Jan 23 at 7:39

Hagen von Eitzen
42.1k23493

Emanuele Paolini · Answer 2 · 2013-01-23 08:04:28Z

up vote 0 down vote

You cannot, since there are infinitely many lines parallel to AB.

answered Jan 23 at 8:04

Emanuele Paolini
3,322113

	sorry! my bad.. the perpendicular distance between the lines is known.. should have mentioned that in the question.. – SatheeshJM Jan 23 at 9:48
	you want ABCD be a rectangle? On which side of AB you want CD to stay? – Emanuele Paolini Jan 23 at 10:12

2 Answers