Dimension of a subspace and its orthogonal complement

Let WβŠ‚R5 be the subspace spanned by the set of vectors {⟨1,βˆ’2,0,2,βˆ’1⟩,βŸ¨βˆ’2,4,βˆ’1,1,2⟩,⟨0,1,2,βˆ’2,1⟩}.

  1. Compute the dimension of W.
  2. Determine the dimension of WβŠ₯, the perpendicular subspace in R5.
  3. Find a basis for WβŠ₯.