Ellipse

On the ellipse \({{{x^2}} \over 8} + {{{y^2}} \over 4} = 1\) let P be a point in the second quadrant such that the tangent at P to the ellipse is perpendicular to the line x + 2y = 0. Let S and S' be the foci of the ellipse and e be its eccentricity. If A is the area of the triangle SPS' then, the value of (5 \(-\) e²). A is :