Question

1-sin x/cos x -cos x /1+sinx

Answer 1

(1-sinx)/cosx - cosx/(1+sinx)=(((1-sinx)(1+sinx))-cosˇ2 x)/(cosx.(1+sinx))=
=(1-sinˇ2x-cosˇ2x)/(cosx.(1+sinx))=(cosˇ2x -cosˇ2x)/(cosx.(1+sinx))=0