Question: how to find the circumference of a circle with points?
Answer: If you have any two points [let,(a1,b1)&(a2,b2)] on circle's diameter,expect the two points on circumference you should find the equation of diameter with-
(x-a1)*(a1-a2)=(y-b1)*(b1-b2)
and then there will be two equations -
(1)E. of circle : (x-h)^2+(y-k)^2=r^2 [let]
(2)E. of diameter : ax+by+c=0 [let]
find the (x,y).