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COMEDK · Maths · 11. Pair of Lines

If two pairs of lines \(x^{2}-2 m x y-y^{2}=0\) and \(x^{2}-2 n x y-y^{2}=0\) are such that one of them represents the bisector of the angles between the other, then

  1. A \(m n=1\)
  2. B \(m+n=m n\)
  3. C \(m n=-1\)
  4. D \(m-n=m n\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(m n=-1\)

Step-by-step Solution

Detailed explanation

The equation of the pair of lines is \(x^{2} - 2mxy - y^{2} = 0\). The angle bisectors of this pair are given by the formula \(\dfrac{x^{2} - y^{2}}{a - b} = \dfrac{xy}{h}\). Here \(a = 1\), \(b = -1\), and \(h = -m\). Substituting these values, we get…