求证sin(a+b)cos(a–b)=sinacosb+sinbcosb
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解决时间 2021-11-15 00:51
- 提问者网友:欺烟
- 2021-11-14 07:54
求证sin(a+b)cos(a–b)=sinacosb+sinbcosb
最佳答案
- 五星知识达人网友:雾月
- 2021-11-14 08:28
好难呀
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- 1楼网友:枭雄戏美人
- 2021-11-14 11:15
展开不就得了啊!
- 2楼网友:煞尾
- 2021-11-14 10:33
sin(a+b)cos(a-b)=(sinna+sinb)(cosa-conb)追答sin(a+b)cos(a-b)=(sina+sinb)(cosa-conb)
- 3楼网友:孤独的牧羊人
- 2021-11-14 08:57
sin(a+b)cos(a–b)
=(sinacosb+cosasinb)(cosacosb+sinasinb)
=sinacosacos^2 b +sin^2 a sinbcosb +cos^2 a sinbcosb +sinacosasin^2 b
=sinacosa(1-sin^2 b) +(1-cos^2 a)sinbcosb +cos^2 a sinbcosb +sinacosasin^2 b
=sinacosa-sinacosasin^2 b +sinbcosb-cos^2 a sinbcosb+cos^2 a sinbcosb +sinacosasin^2 b
=sinacosa+sinbcosb
=(sinacosb+cosasinb)(cosacosb+sinasinb)
=sinacosacos^2 b +sin^2 a sinbcosb +cos^2 a sinbcosb +sinacosasin^2 b
=sinacosa(1-sin^2 b) +(1-cos^2 a)sinbcosb +cos^2 a sinbcosb +sinacosasin^2 b
=sinacosa-sinacosasin^2 b +sinbcosb-cos^2 a sinbcosb+cos^2 a sinbcosb +sinacosasin^2 b
=sinacosa+sinbcosb
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