两直线3ax-y-2=0和(2a-1)x+5ay-1=0 分别过定点A B 则AB长为多少
问题描述:
两直线3ax-y-2=0和(2a-1)x+5ay-1=0 分别过定点A B 则AB长为多少
答
3ax-y-2=0过定点(0,-2)
(2a-1)x+5ay-1=0
2ax-x+5ay-1=0
a(2x+5y)-x-1=0
x=-1
2x+5y=0 ,y=2/5
2ax-x+5ay-1=0过定点(-1,2/5)
AB=根号(1^2+144/25)=根号(169/25)=13/5