Linear Algebra and Its Applications · Problem 3.1.40
Orthogonality — Gilbert Strang
Mathematics · orthogonal-subspaces
Problem
Suppose L is a one-dimensional subspace (a line) in R3. Its orthogonal complement L⊥ is the \_\_\_\_ perpendicular to L. Then (L⊥)⊥ is a \_\_\_\_ perpendicular to L⊥. In fact (L⊥)⊥ is the same as \_\_\_\_.