A circle is of the form x2 + y2 + 2gx + 2fy + c = 0 and a pair of tangents are drawn from (x1, y1) to the circle.The combined equation of tangents is SS1 = T2.
Where S=x2+y2+2gx+2fy+c
S1=x21+y21+2gx1+2fy1+c
T=xx1+yy1+g(x+x1)+f(y+y1)+c
True
This is generally taken as a result. i.e., combined equation of pair of tangents is given by the equation. SS1 = T2