BITSAT 2015 Paper

The equations of the lines are
p1x+q1y -1 = 0 ...(i)
p2x+q2y -1 = 0 ...(ii)
and p3x+q3y -1 = 0 ...(iii)
As they are concurrent,
|

p1	q1	−1
p2	q2	−1
p3	q3	−1

| = 0
⇒ |

p1	q1	1
p2	q2	1
p3	q3	1

| = 0
This is also the condition for the points
(p1,q1), (p2,q2) and (p3,q3) to be collinear