Question 98954
Quadrangle is any general 4 sided polygon.Important is that lines may intersect each other.

{{{drawing( 400, 300, -10, 10, -10, 10, 
line(0,5,5,5),
line(5,5,5,0),
line(5,0,0,10),
line(0,10,0,5),
line(-5,0,0,0),
line (-5,0,0,-5),
line (2,3,0,-5),
line (2,3,0,0)
 )}}}

Theese are two examples of what can quadrangle look like.