题目

已知函数f(x)＝sincos＋cos2－. (1) 若f(α)＝，α∈(0，π)，求α的值； (2) 求函数f(x)在上最大值和最小值． 答案：解：(1) f(x)＝sinx＋－＝ (sinx＋cosx)＝sin.由题意知：f(α)＝sin＝，即sin＝.∵α∈(0，π)，即α＋∈，∴α＋＝，即α＝. (2) ∵ －≤α≤π， 即0≤α＋≤，∴f(x)max＝f（）＝，f(x)min＝f(π)＝－.Your son has kept _________ for two hours. You’d better ask him to have a rest.A．studyB．studiedC．to studyD． studying