[" 5.In "Delta ABC" ,the coordinates of the vertex "A" are "(4,-1)" and lines "x-y-1=0" and "2x-y=3" are the internal "],[" bisecters of angles "B" and "C" .Then,the radius of the incircle of triangle "ABC" is "],[[" (a) "(5)/(sqrt(5))," (b) "(3)/(sqrt(5))," (c) "(6)/(sqrt(5))," (d) "(7)/(sqrt(5))]]