Find the equation of chord of contact of tangents drawn from a point $(x_1,y_1)$ to the ellipse $\large\frac{x^2}{a^2}+\frac{y^2}{b^2}$$=1$.

Question

$\begin{array}{1 1}(a)\;\large\frac{xx_1}{a^2}+\frac{yy_1}{b^2}\normalsize =1\\(b)\;\large\frac{xx_1}{a^2}-\frac{yy_1}{b^2}\normalsize =1\\(c)\;\large\frac{xx_1^2}{a^2}+\frac{yy_1^2}{b^2}\normalsize =1\\(d)\;\text{None of these}\end{array}$