A utility function to calculate area of triangle formed by ( x1 , y1 ) , ( x2 , y2 ) and ( x3 , y3 )
float area ( int x1 , int y1 , int x2 , int y2 , int x3 , int y3 ) { return abs ( ( x1 * ( y2 - y3 ) + x2 * ( y3 - y1 ) + x3 * ( y1 - y2 ) ) / 2.0 ) ; }