What Is a Circle
What is a circle? Any circle is a geometric figure. You can get it in the geometric plane with the canonical inequality:
x2 + y2 ≤ r2
where r - is radius of the circle, D = 2r - is diameter of the circle
(x - m)2 + (y - n)2 ≤ r2
where A(m;n) - is the centre
This is an inequality of the circle with the centre in the point A(m;n).