How to know whether two lines are intersecting or not without drawing them on the graph, when we know their start and end points?



Suppose if AB is a line with A(2,1) and B(6,5) and CD is another line with C(3,4) and D(5,2). If we Draw these two lines on the 2D Graph then these two will intersect. But how could i know that these two lines are going to intersect or not without drawing the line on the 2D Plane?



I will be very thankful to you if u can solve my query and suggest me any other links regarding this. Thanks inadvance. Hoping the earliest reply.

• A(2,1) B(6,5) C(3,4) & D(5,2)
  
  slope of AB = 5-1 / 6-2 = 1
  slope of CD = 2-4 / 5-3 = -1
  
  if slope of two lines is equal then they are parallel otherwise intersecting.
  
  also, (slope of AB)*(slope of CD) = -1
  so, AB & CD are intersecting & perpendicular to each other.
• 10 years agoHelpfull: Yes(0) No(0)