sin^6+COS^6===
问题描述:
sin^6+COS^6===
sin^6+cos^6====
答
sin(x)^6+cos(x)^6 =[sin(x)^2+cos(x)^2]*[sin(x)^4-sin(x)^2*cos(x)^2+cos(x)^4] =sin(x)^4+2*sin(x)^2*cos(x)^2+cos(x)^4-3*sin(x)^2*cos(x)^2 =[sin(x)^2+cos(x)^2]^2-3*sin(x)^2*cos(x)^2 =1-3*sin(x)^2*cos(x)^2 =5/8+3/8*cos(4*x)