Vertices of a parallelogram taken in order are A(2,-1,4) , B(1,0,-1),C(1,2,3) and D. Distance of the point P(8,2,-12) from the plane of the parallelogram is -

n→=7i^+2j^-k^ is normal to plane  , this is AB  X  AC (Assuming n=ai^+bj^+ck^ and using AP¯=6i^+3j^-16k^∴ Distance d=AP¯·n→|n→|=42+6+1649+4+1=6454=6436=64618=3269