Question 295474
circle equation is:
{{{(x - a)^2 + (y - b)^2 = r^2}}}
where (a, b) is the center of the circle, and r is the radius


so, the circle equation with center of (5, -2) and diameter = 8 (radius = 8/2= 4) is:
{{{(x - 5)^2 + (y - (-2))^2 = 4^2}}}
{{{(x - 5)^2 + (y + 2)^2 = 16}}}
{{{(x - 5)*(x - 5) + (y + 2)*(y + 2) = 16}}}
{{{x^2 - 5x - 5x + 25 + y^2 + 2y + 2y + 4 = 16}}}
{{{x^2 - 10x + 25 + y^2 + 4y + 4 - 16 = 0}}}
{{{x^2 + y^2 - 10x + 4y + 25 + 4 - 16 = 0}}}
{{{x^2 + y^2 - 10x + 4y + 13 = 0}}}