题目

 Please put all the magazines _______ on the shelf after you finish reading them. A. in case            B. in place        C. in advance      D. in name 答案：B已知0＜α＜π2，sinα=45．（1）求sin2α+sin2αcos2α+cos2α的值．（2）若0＜β＜π2，且cos（α+β）=513，求cosβ的值．