Circles $C_1$ and $C_2$ have equal radii and are tangent to that same line $L$. Circle $C_3$ is tangent to $C_1$ and $C_2$. $x$ is the distance between the between the centers of $C_1$ and $C_2$. Find the distance $h$, from the center of $C_3$ to line $L$, in terms of $x$ and the radii of the three circles.
this is how much I got:
Let $R_1$, $R_2$ and $R_3$ be the radii of circles $C_1$, $C_2$ and $C_3$ respectively with $R_1 = R_2 = R$, then $h = C_3O + R$
Now how should I go forward. I'm stuck here