Question 852288
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Hi,
 Standard Form of an Equation of an Ellipse is {{{(x-h)^2/b^2 + (y-k)^2/a^2 = 1 }}} 
where Pt(h,k) is the center. (a variable positioned to correspond with major axis)
 a and b  are the respective vertices distances from center
 and ±{{{sqrt(a^2-b^2)}}}are the foci distances from center: a > b
sum of focal radii = 10,  a = 10/2 = 5
  4 = ±{{{sqrt(5^2-b^2)}}}  b = 3
{{{(x-6)^2/3^2 + (y-3)^2/5^2 = 1 }}} 
{{{drawing(300,300,   -10,10,-10,10,  arc(6,3,6,10),
 grid(1),
circle(6, 6,0.4),
circle(6, 0,0.4),
circle(6, 3,0.4),
graph( 300, 300, -10,10,-10,10))}}}