Question 451203
  <pre><font face = "Tohoma" size = 4 color = "indigo"><b> 
Hi,
 Standard Form of an Equation of an Ellipse is {{{(x-h)^2/a^2 + (y-k)^2/b^2 = 1 }}}
where Pt(h,k) is the center and a and b  are the respective vertices distances from center.
endpoints of the major axis are (5,0) and (-5,0)
 {{{x^2/25 + y^2/b^2 = 1}}}
foci (3,0) and (-3,0) sqrt(25-b^2) = 3   b^2 = 16
  {{{x^2/25 + y^2/16 = 1}}}
{{{drawing(300,300,   -10,10,-10,10,  arc(0,0,10,8),
 grid(1),
circle(3, 0,0.4),
circle(-3, 0,0.4),
graph( 300, 300, -10,10,-10,10))}}}