The solution for the equations c1x + b1y + a1 = 0 and c2x + b2y + a2 = 0 is
S1 :x = (b1a2−b2a1)(c1b2−c2b1)
S2 : y =(c1a2−c2a1)(a1b2−a2b1)
If (x1,y1) is a point inside the circle x2+y2+2gx+2fy+c=0 Given two expressions S1 and T1 such that,
S1=x21+y12+2gx1+2fy1+c
T1=xx1+yy1+g(x+x1)+f(y+y1)+c
Then the equation of chord centered at (x1,y1) is