Arun
Last Activity: 6 Years ago
Dear Abhinav
Let, ax+by-1=0 .........1.
ax+y+1=0 …......2.
x+by=0 .........3.
Line passing through the common point of 1, 2 and through origin is 2ax+(1+b)y=0.
Line passing through the common point of 1, 3 and through origin is x+by=0.
The angle between these two lines is 90 degrees then
(-2a/(1+b))(-1/b)=-1
You get it to be 2a+b+b²=0
hence
p = 2
Regards
Arun (askIITians forum expert)