设函数f ( x ) = (sinx – cosx)2 x ÎR .
(1)求f ( x )的最小正周期T;(2)当x为何值时,函数f ( x )取最大值?并求出这个最大值.
设函数f ( x ) = (sinx – cosx)2 x ÎR .
(1)求f ( x )的最小正周期T;(2)当x为何值时,函数f ( x )取最大值?并求出这个最大值.
解 (1) f ( x ) = (1 – 2sinxcosx) =
–
sin2x.
∴ T = p.
(2) x = kp – ( k ÎZ
)时, f ( x )max = 2