⇒<2,−4,2> ∴DR′s=⟨1,−2,1⟩ or ⟨−1,2,−1⟩ Hence, DC′s=
−1
√6
,
2
√6
,
−1
√6
Or Let DR′ 's of normal is α,β and γ According to question, α+2β+3γ=0. . . (i) and −α+0β+γ=0 . . . (ii) On solving Eqs. (i) and (ii) by cross-multiplication,