α∈IV ćwiartki ( sinα<0, cosα>0) [latex]( frac{1+cos alpha }{ sqrt{1-cos ^{2} alpha })} - frac{sin alpha }{1+ sqrt{1-sin ^{2} alpha }})*sin alpha = [/latex][latex] frac{(1+cos alpha) }{Isin alpha I}*sin alpha - frac{sin alpha }{(1+Icos alpha I)}*sin alpha = [/latex][latex] frac{(1+cos alpha )}{-sin alpha }*sin alpha - frac{sin ^{2} alpha }{1+cos alpha }= [/latex] [latex]-(1+cos alpha )- frac{sin ^{2} alpha }{1+cos alpha }= frac{-(1+cos alpha )(1+cos alpha )}{1+cos alpha }- frac{sin ^{2} alpha }{1+cos alpha }= [/latex][latex] frac{-1-2cos alpha -cos ^{2} alpha -sin ^{2 } alpha }{1+cos alpha }= frac{-2-2cos alpha }{1+cos alpha }= [/latex] [latex] frac{-2(1+cos alpha )}{1+cos alpha }=-2 [/latex]
