question_answer

If the given planes \[ax+by+cz+d=0\] and \[a'x+b'y+c'z+d'=0\] be mutually perpendicular, then            [MP PET 1994]

A)            \[\frac{a}{a'}=\frac{b}{b'}=\frac{c}{c'}\]

B)            \[\frac{a}{a'}+\frac{b}{b'}+\frac{c}{c'}=0\]

C)            \[aa\,'+\,bb\,'+\,cc\,'+\,dd\,'=0\]

D)            \[aa\,'+\,bb\,'+\,cc\,'=0\]