Hey guys i am noy able to solve this problem.So please do help me in solving this.The equation of common tangent to ellipse 

\begin{equation\*}
x^2 +2y^2=1
\end{equation\*}

and circle 

\begin{equation\*}
x^2 +y^2=\frac{2}{3}
\end{equation\*}
is?