VITEEE 2011 Paper

The equation of the bisectors of the angle between the lines given by
ax2 + 2hxy + by2 = 0 is

x2−y2

a−b

=

xy

h

... (i)
And the equation of the bisectors of the angle between the lines given by
a2x2 + 2h (a + b) xy + b2y2 = 0 is

x2−y2

a−b

=

xy

h(a+b)

⇒

x2−y2

a−b

=

x

h

... (ii)
From eqs. (i) and (ii), it is clear that both the pair of straight lines have the same bisector, hence, the given two pairs of straight lines are equally inclined.