1-sin^2x/sinx cosx=ctgx-tgx

[latex] \frac{1-sin^{2}x}{sinxcosx} = ctgx-tgx[/latex]; [latex]\frac{ cos^{2}x }{sinxcosx} =ctgx-tgx[/latex]; [latex]ctgx=ctgx-tgx[/latex] ; [latex]tgx=0[/latex] ; [latex]x= \pi n, n[/latex]∈ Z