The image D of A in the bisector of `angle B` lies on BC.
Now, the image of A(1,2) in the line 2x-y-10=0 is given by
`(x_(1)-1)/(2) = (y_(1)-2)/(-1) = (-2(2-2+10))/(4+1)`
. `therefore D(x_(1), y_(1)) -=D(-7,6)`
Also, C is the image of A in the perpendicular bisector of AC. The image of A(1,2) in y=x is C(2,1).
Hence the equation of line BC is
. `y-1 = (6-1)/(-7-2)(x-2)`
or 5x+9y-19=0