$\noindent The hyperbola is: $\frac{x^2}{4^2}-y^2 = 1$. Now, use the fact that the equation of the chord of contact from the point $\left(x_0,y_0\right)$ to the hyperbola $\frac{x^2}{a^2}-\frac{y^2}{b^2}=1$ is $\frac{x_0 x}{a^2}-\frac{y_0y}{b^2}=1$, assuming such a chord exists (which'll happen...