Question 852474
<pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi,
vertices:(15, 5), (1,5)  
          C(8,5)   {{{(15 + 1)/2 = 8}}}, a = 7  (8+7 = 15)
 {{{(x-8)^2/7^2 + (y-5)^2/b^2 = 1 }}} 
foci:(8+ &#8730;13,5), (8- &#8730;13,5) ± {{{sqt(13) = sqrt(7^2-b^2)}}} b = 6
{{{(x-8)^2/7^2 + (y-5)^2/6^2 = 1 }}} 
 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. (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
{{{drawing(300,300,   -30,30,-30,30,  arc(8,5,14,12),
 grid(1),
circle( 15,5, 0.4),
circle(1, 5,0.4),
graph( 300, 300, -30,30,-30,30))}}}