Plotting triangle and finding its vertices

hi!! I want to plot these lines, find the point of intersection formed by these lines. The plot is not intersecting these, though they should graphically. How do I make them intersect and find the vertices formed?

 [x1] = input('Enter the value of 1st coord');
  [y1] = input('Enter the value of 2nd coord');
  t = linspace(0,1);
  xa = x1(1)+ (y1(1)-x1(1))*t;
  ya = y1(1) + (y1(2)-x1(2))*t;
  [x2] = input('Enter the value of 1st coord');
  [y2] = input('Enter the value of 1st coord');
  u = linspace(0,1);
  xb = x2(1)+ (y2(1)-x2(1))*u;
  yb = y2(1) + (y2(2)-x2(2))*u;
  [x3] = input('Enter the value of 1st coord');
  [y3] = input('Enter the value of 1st coord');
  v = linspace(0,1);
  xc = x3(1)+(y3(1)-x3(1))*v;
  yc = y3(1)+(y3(2)-x3(2))*v;
  plot(xa,ya,xb,yb,xc,yc);