已知sin(x+30)=12/13,且60

来源:学生作业帮助网 编辑:六六作业网 时间:2024/12/25 13:46:21
已知sin(x+30)=12/13,且60已知sin(x+30)=12/13,且60已知sin(x+30)=12/13,且60sinx=sin((x+30)-30)=sin(x+30)c0s30-co

已知sin(x+30)=12/13,且60
已知sin(x+30)=12/13,且60

已知sin(x+30)=12/13,且60
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