Find the equation of tangent and normal to the ellipse `(x^(2))/(a^(2)) + (y^(2))/(b^(2)) = "1 at" (x_(1), y_(1))`.

Answer

`(x x_(1))/(a^(2)) + (y y_(1))/(b^(2)) = 1, (a^(2)x)/(x_(1)) - (b^(2)y)/(y_(1)) = a^(2) - b^(2)`