已知在△ABC中,a、b、c所对的边,且a=4,b+c=5,tanB+tanC+根号3=根号3tanBtanC,则△ABC的面积为黄冈密卷的答案是3倍根号3/4∵tanB+tanC+√3 =√3tanBtanC∴tanB+tanC=-(√3-√3tanBtanC)=-√3(1-tanBtanC)∴(tanB+tanC)/(1-tanB
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/01 07:15:23
![已知在△ABC中,a、b、c所对的边,且a=4,b+c=5,tanB+tanC+根号3=根号3tanBtanC,则△ABC的面积为黄冈密卷的答案是3倍根号3/4∵tanB+tanC+√3 =√3tanBtanC∴tanB+tanC=-(√3-√3tanBtanC)=-√3(1-tanBtanC)∴(tanB+tanC)/(1-tanB](/uploads/image/z/987394-58-4.jpg?t=%E5%B7%B2%E7%9F%A5%E5%9C%A8%E2%96%B3ABC%E4%B8%AD%2Ca%E3%80%81b%E3%80%81c%E6%89%80%E5%AF%B9%E7%9A%84%E8%BE%B9%2C%E4%B8%94a%3D4%2Cb%2Bc%3D5%2CtanB%2BtanC%2B%E6%A0%B9%E5%8F%B73%3D%E6%A0%B9%E5%8F%B73tanBtanC%2C%E5%88%99%E2%96%B3ABC%E7%9A%84%E9%9D%A2%E7%A7%AF%E4%B8%BA%E9%BB%84%E5%86%88%E5%AF%86%E5%8D%B7%E7%9A%84%E7%AD%94%E6%A1%88%E6%98%AF3%E5%80%8D%E6%A0%B9%E5%8F%B73%2F4%E2%88%B5tanB%2BtanC%2B%E2%88%9A3+%3D%E2%88%9A3tanBtanC%E2%88%B4tanB%2BtanC%3D-%28%E2%88%9A3-%E2%88%9A3tanBtanC%29%3D-%E2%88%9A3%281-tanBtanC%29%E2%88%B4%28tanB%2BtanC%29%2F%281-tanB)
已知在△ABC中,a、b、c所对的边,且a=4,b+c=5,tanB+tanC+根号3=根号3tanBtanC,则△ABC的面积为黄冈密卷的答案是3倍根号3/4∵tanB+tanC+√3 =√3tanBtanC∴tanB+tanC=-(√3-√3tanBtanC)=-√3(1-tanBtanC)∴(tanB+tanC)/(1-tanB
已知在△ABC中,a、b、c所对的边,且a=4,b+c=5,tanB+tanC+根号3=根号3tanBtanC,则△ABC的面积为
黄冈密卷的答案是
3倍根号3/4
∵tanB+tanC+√3 =√3tanBtanC
∴tanB+tanC=-(√3-√3tanBtanC)
=-√3(1-tanBtanC)
∴(tanB+tanC)/(1-tanBtanC)=-√3
=tan(B+C)
=tan(π-A)
=-tanA
∴tanA=√3
∵A∈(0,π)
∴A=π/3
有正玄定理:a²=b²+c²-2bccosA
∴b²+c²-bc=16
又因为b+c=5=>(b+c)²=25=b²+c²+2bc
∴bc=3
∴S=1/2sinAbc=√3/4
我错在哪里
已知在△ABC中,a、b、c所对的边,且a=4,b+c=5,tanB+tanC+根号3=根号3tanBtanC,则△ABC的面积为黄冈密卷的答案是3倍根号3/4∵tanB+tanC+√3 =√3tanBtanC∴tanB+tanC=-(√3-√3tanBtanC)=-√3(1-tanBtanC)∴(tanB+tanC)/(1-tanB
S=1/2sinA*bc
=1/2*√3/2*3
=3倍的根号3/4
你就是最后结果算错了
问你数学老师
你没错啊!就是这样的!