问题 问答题

菱形ABCD的中心为M(0,1),又知道A(1,-1)和AB所在直线的方程为x+y=0.求另外三条边的方程.

答案

参考答案:CD:x+y-2=0;AD:7x+y-6=0;BC:7x+y+4=0.

解析: 求CD所在直线的方程,设为x+y+c=0,用M到各边的距离相等求c.
求AD所在直线的方程,设为a(x-1)+b(y+1)=0(因为它过点A(1,-1)),再利用M到各边的距离相等求出a和b的比值.

阅读理解

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问答题 简答题