Question

If the pair of straight lines `x^2 - 2pxy - y^2 = 0` and `x^2 - 2qxy -y^2 = 0` be such that each pair bisects the angle between the other pair, then
A. `pq=-1`
B. `pq=1`
C. `1/p+1/q=0`
D. `1/p-1/q=0`

Answer 1

Correct Answer - A
Since, `x^(2)+(2xy)/(p)-y^(2)=0,` is the angle bisectors of `x^(2)-2pxy-y^(2)=0`
But given that angle bisectors are
`x^(2)-2qxy-y^(2)=0`
`therefore-2q=2//p`
`impliespq=-1`