if (mi,1mi), i=1,2,3,4 are four distinct points on a circle,
then m1m2m3m4=
Let the points (mi,1mi),i=1,2,3,4 lie on the circle x2+y2+2gx+2fy+c=0⇒m2i+1m2i+2gmi+2fmi+c=0, i=1,2,3,4⇒ m4i+2gm3i+cm2i+1=0,i=1,2,3,4
Now, m1,m2,m3,m4 are roots of the equation.
∴ m1⋅m2⋅m3⋅m4=1