We know that `tan^(-1)=-pi+cot^(-1)(1/x)if xlt0`
`therefore {tan^(-1)(1-x^(2))/(2x) -cosf^(-1)(1-x^(2))/(1+x^(2))}`
`=sin{-pi+co^(-1)(2x)/(1-x^(2))-cos^(-1)(1-x^(2))/(1+x^(2))}`
`=sin{-(pi)/(2)-2tn^(-2)tan^(-1)x+2tan^(-1)x+2tan^(-1)x}`
`=sin(-(pi)/(2))=-1`