已知函数f(x)= cos(x+ ),x∈R. (1)求函数f(x)的在[﹣ , ]上的值域; (2)若θ∈(0, ),且f(θ)= ,求sin2θ的值. 答案:(1)解:∵ ,∴ , 由 的图象可知, , ∴ . (2)解:∵ , , ∴ , ∴ , ∴ . 【解析】(1)由条件利用余弦函数的定义域和值域,求得函数f(x)的在[﹣ , ]上的值域.(2)利用二倍角公式求得cos(θ+ )的值,再利用诱导公式求得sin2θ的值.He tried his best to help you, so I think you should make a gift on his birthday.A.he; myself B.him; himself C.him; yourself