f（x）=（1+cotx）sin^2x+Msin(x+∏／4)sin(x-∏／4)=（sinx+cosx）sinx + (√2/2)M(sinx+cosx)(sinx-cosx)tana = sina/cosa = 2; sina = 2cosaf（a）= 3cosa 2cosa + (√2/2)M(3cosa)(cosa)=[6+(3√2/2)M]cos^2(a) ...