Find the equations of the tangent planes to the sphere $x^2+y^2+z^2-10x+2y+26z-113=0$ which are parallel to the straight lines $\frac{x+5}{2}=\frac{y-1}{-3}=\frac{z+13}{2}$ and $\frac{x+7}{3}=\frac{y+1}{-2}=\frac{z-8}{8}$.
Attempt:
Let the tangent plane be:
$ax+by+cz+d=0$ It is parallel to the given two straight line, so we have $2a-3b+2c=0, ~~3a-2b+8c=0$ Cross-multipling
$$\frac{a}{4}=\frac{b}{2}=\frac{c}{-1}$$
My process shall not give me answer. Please help.