Given that point P(a cos θ, b sin θ) is a point on
the ellipse (x^2 /a^2 )+(y^2 /b^2 )=1.
The tangent to the curve at point P is perpendicular
to a straight line which passes through the focus,
F (ae,0). If N is the intersection point, show that
the equation of the locus of N is x^2 +y^2 =a^2 .