Find the equation of a straight line in the plane r→⋅n→=d  which  parallel to r→=a→+λb→ and passes through the foot of the perpendicular drawn from point  P(a→) to r→⋅n→=d( where n→⋅b→=0)

Foot of the perpendicular from point Aa→ on the plane r→⋅n→=d is a→+(d−a→⋅n→)|n→|2n→Therefore, equation of the line parallel to r→=a→+λb→  in the planer→⋅n→=d is given byr→=a→+(d−a→⋅n→)|n→|2n→+λb→