Find the projection of AP Along 11 mid then calculate d, the distance from P to the plane. The line segment of length d and the vector n are both perpendicular to the plane. Solution Projection of AP along n = (AP.n)/(n.n) n = [(3,4,2).(2,2,-1)/(2,2,-1).(2,2,-1)] <2,2,-1> = (12/9) <2,2,-1> = <8/3 , 8/3 , -4/3> d = (8/3)^2 + (8/3)^2 + (-4/3)^2 = (64/9 + 64/9 + 16/9) = 4.