Question 425642
This ellipse is centered at the origin and has a horizontal axis of length 16 and a vertical axis of length 8. What is its equation?

..

Standard form for this ellipse:
(x-h)^2/a^2+(y-k)^2/b^2=1,(a>b) with (h,k) being the (x,y) coordinates of the center.
In this case since the center is at (0,0) the equation becomes:
x^2/a^2+y^2/b^2=1 (a>b) All we need to do is find a^2 & b^2 to get the equation.
..

2a=major axis as given =16
a=8
a^2=64
2b=minor axis as given = 8
b=4
b^2=16

Equation of the ellipse:
x^2/64+y^2/16=1
The graph below shows what this ellipse looks like.

..
y=+-(16(1-x^2/64))^.5
{{{ graph( 300, 300, -10, 10, -10, 10, (16(1-x^2/64))^.5,-(16(1-x^2/64))^.5) }}}