已知sin(x+30)=12/13,且60

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已知sin(x+30)=12/13,且60

数学人气:287 ℃时间:2020-09-14 08:51:15
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sinx=sin((x+30)-30)=sin(x+30)c0s30-cos(x+30)sin30,因为sin(x+30)=12/13所以cos(x+30)=5/13,代入上式可得
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sinx=sin((x+30)-30)=sin(x+30)c0s30-cos(x+30)sin30,因为sin(x+30)=12/13所以cos(x+30)=5/13,代入上式可得