∫1/（sinx）dx =∫cscxdx =∫sinx/(1-cos²x) dx =-∫dcosx/(1-cos²x) =-1/2[∫dcosx/(1-cosx)+∫dcosx/(1+cosx)] = -1/2[∫-d(1-cosx)/(1-cosx)+∫d(1+cosx)/(1+cosx)] =-1/2ln(1+cosx)/ (1-cosx)+C =ln[...