sina+sin3a为什么等于2sin2acosa?
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/07/25 00:10:34
sina+sin3a为什么等于2sin2acosa?
![sina+sin3a为什么等于2sin2acosa?](/uploads/image/z/20047480-16-0.jpg?t=sina%2Bsin3a%E4%B8%BA%E4%BB%80%E4%B9%88%E7%AD%89%E4%BA%8E2sin2acosa%3F)
sina+sin3a
=sin(2a-a)+sin(2a+a)
=sin2acosa-cos2asina+sin2acosa+cos2asina
=2sin2acosa
=sin(2a-a)+sin(2a+a)
=sin2acosa-cos2asina+sin2acosa+cos2asina
=2sin2acosa
化简:SinA+2Sin3A+Sin5A/Sin3A+2Sin5A+Sin7A
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