sin(wt–a)如何化余弦 sin(a+b)转换为余弦
sin\u5982\u4f55\u53d8\u6210cossin(\u03c0/2-a)=cosa\u6216\u8005sin(\u03c0/2+a)=cosa\u3002
\u03c0/2\u00b1\u03b1\u4e0e\u03b1\u7684\u4e09\u89d2\u51fd\u6570\u503c\u4e4b\u95f4\u7684\u5173\u7cfb\uff1a
sin\uff08\u03c0/2+\u03b1\uff09=cos\u03b1
sin\uff08\u03c0/2\uff0d\u03b1\uff09=cos\u03b1
cos\uff08\u03c0/2+\u03b1\uff09=\uff0dsin\u03b1
cos\uff08\u03c0/2\uff0d\u03b1\uff09=sin\u03b1
tan\uff08\u03c0/2+\u03b1\uff09=\uff0dcot\u03b1
tan\uff08\u03c0/2\uff0d\u03b1\uff09=cot\u03b1
cot\uff08\u03c0/2+\u03b1\uff09=\uff0dtan\u03b1
cot\uff08\u03c0/2\uff0d\u03b1\uff09=tan\u03b1
\u6269\u5c55\u8d44\u6599\uff1a
\u8bf1\u5bfc\u516c\u5f0f\u53e3\u8bc0\u201c\u5947\u53d8\u5076\u4e0d\u53d8\uff0c\u7b26\u53f7\u770b\u8c61\u9650\u201d\u610f\u4e49\uff1a
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\u672c\u8d28\u662f\u4efb\u4f55\u89d2\u7684\u96c6\u5408\u4e0e\u4e00\u4e2a\u6bd4\u503c\u7684\u96c6\u5408\u7684\u53d8\u91cf\u4e4b\u95f4\u7684\u6620\u5c04\u3002\u901a\u5e38\u7684\u4e09\u89d2\u51fd\u6570\u662f\u5728\u5e73\u9762\u76f4\u89d2\u5750\u6807\u7cfb\u4e2d\u5b9a\u4e49\u7684\u3002\u5176\u5b9a\u4e49\u57df\u4e3a\u6574\u4e2a\u5b9e\u6570\u57df\u3002\u53e6\u4e00\u79cd\u5b9a\u4e49\u662f\u5728\u76f4\u89d2\u4e09\u89d2\u5f62\u4e2d\uff0c\u4f46\u5e76\u4e0d\u5b8c\u5168\u3002\u73b0\u4ee3\u6570\u5b66\u628a\u5b83\u4eec\u63cf\u8ff0\u6210\u65e0\u7a77\u6570\u5217\u7684\u6781\u9650\u548c\u5fae\u5206\u65b9\u7a0b\u7684\u89e3\uff0c\u5c06\u5176\u5b9a\u4e49\u6269\u5c55\u5230\u590d\u6570\u7cfb\u3002
\u8bb0\u80cc\u8bc0\u7a8d\uff1a\u5947\u53d8\u5076\u4e0d\u53d8\uff0c\u7b26\u53f7\u770b\u8c61\u9650\uff0c\u5373\u5f62\u5982\uff082k+1\uff0990\u00b0\u00b1\u03b1\uff0c\u5219\u51fd\u6570\u540d\u79f0\u53d8\u4e3a\u4f59\u540d\u51fd\u6570\uff0c\u6b63\u5f26\u53d8\u4f59\u5f26\uff0c\u4f59\u5f26\u53d8\u6b63\u5f26\uff0c\u6b63\u5207\u53d8\u4f59\u5207\uff0c\u4f59\u5207\u53d8\u6b63\u5207\u3002\u5f62\u59822k\u00d790\u00b0\u00b1\u03b1\uff0c\u5219\u51fd\u6570\u540d\u79f0\u4e0d\u53d8\u3002
\u53c2\u8003\u8d44\u6599\u6765\u6e90\uff1a\u767e\u5ea6\u767e\u79d1\u2014\u2014\u4e09\u89d2\u51fd\u6570\u516c\u5f0f
sin\uff08A+B\uff09=cos\uff08\u03c0/2-A-B\uff09\uff0c
sin\uff08A+B\uff09=sinAcosB+cosAsinB
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