Respuesta :

−[cos2(x)(sin(x)+1)(sin(x)−1)] / [(sin(x)+1)(sin(x)−1)] I belive is the answer 

formula
cos(pi - x) = -cos(x)
cos^2(x) + sin^2(x) = 1

i think you mean this
cos^2(pi-x) / sqrt[ 1-sin^2(x) ]
= cos^2(x) / sqrt[ cos^2(x) ]
= cos^2(x) / | cos(x) |
= | cos(x) |

if so, none is correct