解: ··················································· 2分
································································· 5分 ·············································································· 6分 ······················································································· 7分 (1) 的最小正周期···································································· 8分 (2) 由得 ∴的单调减区间为··············································· 10分 (3)
∵ ∴ ∴ ∴ 即的值域为··············································································· 12分 |