已知sin（π4+3α）sin（π4-3α）=14，α∈（0，π4），求（1-c 发布时间：2017-04-22 23:21 │ 来源：www.tikuol.com 题型：解答题 问题： 已知sin（π4+3α） sin（π4-3α）=14，α∈（0，π4），求（1-cos2αsin2α-3）sin4α的值．
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题型：解答题 甲公司向乙公司发出一份要约，想购买一批建筑材料。乙公司做出承诺后，由于原材料价格飞涨而拟撤回承诺。下列说法中，不正确的是( )。A．撤回承诺的通知与承诺通知同时到达甲公司也可撤回B．该承诺可以撤回C．撤回承诺的通知在承诺通知到达甲公司之前发出即可D．撤回承诺的通知先于承诺通知到达甲公司之前即可撤回 查看答案