Question

下图xa1-xb4,y1-y4为采用

这一步怎么划到这一步
(x1+x2)(x1-x2)/4+(y1+y2)(y1-y2)/3=0 ==> (y1-y2)/(x1-x2)+3/4*[(x1+x2)/(y1+y2)]=0

Answer 1

(x1+x2)(x1-x2)/4+(y1+y2)(y1-y2)/3=0相当于(x1+x2)(x1-x2)/4=-(y1+y2)(y1-y2)/3
即(y1-y2)/(x1-x2)=3/4*[(x1+x2)/(y1+y2)],移项就得到了.