已知ABC三点的圆角ABC三个顶点,是A(2,-4),B(0,3,(-6,0),求AC边上中线BD的长度


已知三角形ABC的一个顶点A(2,-4),且∠B,∠C的内角平分线所在的直线的方程依次是x+y-2=0,x-3y-6=0,求ABC的三边所在直线的方程...
已知三角形ABC的一个顶点A(2,-4),且∠B,∠C的内角平分线所在的直线的方程依次是x+y-2=0,x-3y-6=0,求ABC的三边所在直线的方程
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展开全部过A(2,-4)作x+y-2=0的对称点A1,A1(6,0)A1在直线BC上也在x-3y-6=0,而x-3y-6=0上有一点是C假设A1与C不重合,则A1C就确定一条直线即BC,不符合题意故A1与C重合,C(6,0)过A(2,-4)作x-3y-6=0的对称点A2(0.4,0.8)直线A2C方程为y=(-x/7)+(6/7)联立y=(-x/7)+(6/7)与x+y-2=0,解得x=4/3,y=2/3,所以B点坐标(4/3,2/3)A,B,C三点坐标知道后就自己求三边直线方程',getTip:function(t,e){return t.renderTip(e.getAttribute(t.triangularSign),e.getAttribute("jubao"))},getILeft:function(t,e){return t.left+e.offsetWidth/2-e.tip.offsetWidth/2},getSHtml:function(t,e,n){return t.tpl.replace(/\{\{#href\}\}/g,e).replace(/\{\{#jubao\}\}/g,n)}},baobiao:{triangularSign:"data-baobiao",tpl:'{{#baobiao_text}}',getTip:function(t,e){return t.renderTip(e.getAttribute(t.triangularSign))},getILeft:function(t,e){return t.left-21},getSHtml:function(t,e,n){return t.tpl.replace(/\{\{#baobiao_text\}\}/g,e)}}};function l(t){return this.type=t.type
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1.求AC边上中线所在直线的方程2.求AC边上的中垂线所在直线的方程3.求AC边上的高所在直线的方程...
1.求AC边上中线所在直线的方程2.求AC边上的中垂线所在直线的方程3.求AC边上的高所在直线的方程
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  解:(1)由中点坐标公式知:AC的中点坐标为(-1,5)  设直线BC的解析式为 :y=k1x+b1  那么  解得  所以AC边上中线所在直线的方程为y=、、、、省略了其他两个没有做出来,不好意思。已赞过已踩过你对这个回答的评价是?评论
收起1.AC中点为(-1,5)设出来方程Y=KX+b后代入解出来就行了。2.求出AC斜率,K=-1,AC中垂线斜率和AC斜率乘积为-1,求AC中垂线的斜率为1,再把(-1,5)代入求出b3.AC高线斜率与2中的相等是1,一个求法,然后将A(0,4)代入就行了1.AC边中点坐标为(-1,5),B点为(-4,0),所以直线为5x-3y+20=02.AC斜率为-1,所以中垂线斜率为1,中点为(-1,5),所以直线为y=x+63.AC斜率为-1,所以高的斜率为1,B点坐标(-4,0),所以直线为y=x+4如图可以算出三角形ABC的面积是40三角形DBC的面积是20可以计算出D点的纵坐标是4D点在直线AC上,A和C的坐标已知,可以求出直线AC的方程D点的纵坐标4代入直线AC的方程,可以求出D点的坐标由B和D的坐标可以求出过点B且将三角形ABC面积平分的直线方程自己计算吧

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