關於vexs的科普知識

1.定點A(設M(x,y)向量AM=(x+1,y)向量BM=(x-1,y)點M到點C(0,1)距離平方爲：x^2+(y-1)^2向量AM乘向量BM:(x+1)(x-1)+y^2=x^2-1+y^2x^2-1+y^2=k*[x^2+(y-1)^2](k-1)x^2+(k-1)y^2+k-2ky+1=0...