a⊥b x1x2+y1y2=0即 (sinx-cosx)(sinx+cosx) + 2cosxsinx = 0sin^2 (x) - cos^2 (x) + 2cosxsinx = 0-cos(2x) + sin(2x) = 0cos(2x) = sin(2x)tan(2x) = sin(2x)/cos(2x) = 1 a*b = x1x2 + y1y2 = 3/5即 (sinx-cosx)...