函数y=cos^2x-sin^2x+2sinxcosx(x∈R)的值域为

问题描述:

函数y=cos^2x-sin^2x+2sinxcosx(x∈R)的值域为

y=cos^2x-sin^2x+2sinxcosx
=cos2x+sin2x
=根号2 sin(2x+π/4)
-1