Determine whether two segments P1Q1 and P2Q2 have a common point if the (x,y) coordinates of their end points is known?

Does this question have a solution? I think it's impossible to know if line segments P1Q1 and P2Q2 intersect at all with just the information about their end points Q1 and Q2.

Thanks.

• The co-ordinates of only their end points are known (I guess this is not the terminology that is used in math, but that's what I meant). So we know only the co-ordinates of Q1 and Q2. – theprogrammer Mar 3 '16 at 8:37

The condition "if the $(x,y)$ coordinates of their end points is known" almost certainly means that the coordinates of all four end points is known, namely $P_1,Q_1,P_2,Q_2$. In the usual terminology, each line segment has two end points, not a start point and an end point.