1.m*n=2cos^2+2cosxsinx=0 化碰漏简 cos2x+sin2x-1=√2*sin(睁吵纯2x+π/4)-1=0sin(2x+π/4)=√2/2 2x+π/4=2kπ+π/4或者2kπ+3π/4 x=π/42.f(x)=√2*sin(悉咐2x+π/4)-1 字数太多,写不下