求函数f(x)=5根号3cos^2x 根号3sin^2x-4sinxcosx(兀/4
问题描述：
求函数f(x)=5根号3cos^2x 根号3sin^2x-4sinxcosx(兀/4
前面是f(x)=5根号3cos^2x加根号3sin^2x减4sinxcosx
答
(sqrt是开方)f(x) = 5sqrt(3) [cos(2x)]^2 + sqrt(3) [sin(2x)]^2 - 4sin(x)cos(x),由于 [cos(2x)]^2 + [sin(2x)]^2 = 1,且 2sin(x)cos(x) = sin(2x),故= 5sqrt(3) {1-[sin(2x)]^2} + sqrt(3) [sin(2x)]^2 - 2sin(2x...