Given that the line y=mx+c is a tangent to the circle

Question

(x-a)^2+(y-b)^2 = r^2

show that:

(1-m^2)r^2=(c-b+ma)^2

Please Help and sorry for the inconvenience

Answer 1

Steve did this same question here:

http://www.jiskha.com/display.cgi?id=1493739139