The line  intersect the curve  at points  and . The circle on  as diameter passes through the origin. Then the value of  is

(9)

     (1)

Also     (2)

Now homogenising (2) with the help of (1), we gets

    (3)

This is the equation of pair of straight lines  and

Now  is diameter, then  and  are perpendicular

coefficient of  coeffiecient of