Because of symmetry, x0>0, y0>0 = = =>s triangle OAB = | OA |||| OB |/2 = 2/(x0y0).
x0^2/4+y0^2= 1===>; 1 & gt; = 2 * x0/2 * y0 = x0 y0 & gt; 0 = = = & gt 1/(x0y0)>= 1 = = = >; S & gt=2.