A straight line ¯r=¯a+λ¯b meets the plane ¯r.¯n=0 in R then P.V of R is given by
Vector equation of a straight line passing through a point given by position vector ¯a parallel to ¯b be is given by ¯r=¯a−λ ¯b, where ¯r , where ¯r is r position vector of a general point on the line and λϵIR