Find the length of common chord of two intersecting circles Let us consider two intersection circles 
$x^2+y^2+2g_1x+2f_1y+c_1=0$  
and  $x^2+y^2+2g_2x+2f_2y+c=0$.
Then equation of common chord of the above two circles is
\begin{equation}2(g_1-g_2)x+2(f_1-f_2)y+c_1-c_2=0............(1)
\end{equation}
I want to find the length of the chord (1).
Any one help me to find out the length of chord.
Thank you.

Hint:
If you want to use the equation of the line $2(g_1-g_2)x+2(f_1-f_2)y+c_1-c_2=0$, intersects this line with a circle (i.e. solve the system of the two equations), so you find the two common points of the two circles, than take the distance form these.
