Coordinate Geometry

If the pair of straight lines x2 - 2pxy - y2 = 0 and x2 - 2qxy - y2 = 0 be such that each pair bisects the angle between the other pair, then

  1. pq = -1
  2. p = -q
  3. pq = 1
  4. p = q

Answer

Equation of bisector of both pair of straight lines,

px2 + 2xy - py2 = 0

qx2 + 2xy - qy2 = 0

q/1 = 2/-2p = -q/-1

The correct option is A.