Question 421929
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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 with a and b determining the respective vertices distances from center.
x^2/9+y^2/16=1
Center(0,0)  Vertices: (3,0),(-3,0) and (0,4),(0,4)
foci distance from center along major axis: {{{sqrt(16-9) = sqrt(7)}}}
foci: (0,sqrt(7)),(0,-sqrt(7))
{{{drawing(300,300,   -10,10,-10,10,  arc(0,0,6,8),
 grid(1),
circle(0,2.646,0.4),
circle(0, -2.646,0.4),
graph( 300, 300, -10,10,-10,10))}}}