equation of tangent to ellipse in slope form

Equation of Tangent to Ellipse $x^2\over a^2$ + $y^2\over b^2$ = 1 : (a) Point form : The equation of tangent to the given ellipse at its point ($x_1, y_1$) is  $x{x_1}\over a^2$ + $y{y_1}\over b^2$ = 1. Note – For general ellipse replace $x^2$ by $xx_1$, $y^2$ by $yy_1$, 2x by $x + x_1$, […]