def line2d(p0, p1):
 (x0, y0) = p0[:2]
 (x1, y1) = p1[:2]
 if (x0 == x1):
  a = (-1)
  b = 0
  c = x1
 elif (y0 == y1):
  a = 0
  b = 1
  c = (- y1)
 else:
  a = (y0 - y1)
  b = (x0 - x1)
  c = ((x0 * y1) - (x1 * y0))
 return (a, b, c)

def line2d ( p0 , p1 ) : ( x0 , y0 ) = p0 [ : 2 ] ( x1 , y1 ) = p1 [ : 2 ] if ( x0 == x1 ) : a = ( - 1 ) b = 0 c = x1 elif ( y0 == y1 ) : a = 0 b = 1 c = ( - y1 ) else : a = ( y0 - y1 ) b = ( x0 - x1 ) c = ( ( x0 * y1 ) - ( x1 * y0 ) ) return ( a , b , c )
return 2d equation of line in the form ax+by+c = 0 .