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和差化积公式速记口诀
更新时间: 2021-01-19 09:03:45  

1、正加正,正在前:sin α+sinβ=2sin[(α+β)/2]·cos[(α-β)/2]

2、正减正,余在前:sin α-sin β=2cos[(α+β)/2]·sin[(α-β)/2]

3、余加余,余并肩:cos α+cos β=2cos[(α+β)/2]·cos[(α-β)/2]

4、余减余,余不见,负号很讨厌:cos α-cos β=-2sin[(α+β)/2]·sin[(α-β)/2]

关键词: 公式 速记 口诀

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