[tex]-sinx = (cotx-cscx)(cosx+1) \\ \\ -sinx = ( \frac{cosx}{sinx} - \frac{1}{sinx})(cosx+1) \\ \\ -sinx = (\frac{cosx-1}{sinx})(cosx+1) \\ \\ -sinx = \frac{cos^2x-1}{sinx} \\ \\ -sinx = \frac{-sin^2x}{sinx} \\ \\ -sinx =-sinx[/tex]
Identity used:
from 4th line to 5th line: sin²x + cos²x = 1
