# Condition of Concurrency of Three Lines

Let

*a*_{1}*x*+*b*_{1 }*y*+*c*_{1}= 0 ...(1)*a*

_{2}

*x*+

*b*

_{2}

*y*+

*c*

_{2}= 0 ...(2)

*a*

_{3}

*x*+

*b*

_{3}

*y*+

*c*

_{3}= 0 ...(3)

be three concurrent lines. Then the point of intersection of (1) and (2) must lie on the third.

â‡’ = 0

# Distance of a point from a line

The length of the perpendicular from a point (

*x*_{1},*y*_{1}) on a line*ax*+*by*+*c*= 0 is# Distance between two parallel lines

Distance between two parallel lines

*ax*+*by*+*c*= 0 and*ax*+*by*+*c*_{1}= 0 is*p*=