Check the true statements below:
A. The orthogonal projection of y onto v is the same as the
orthogonal projection of y onto cv whenever c≠0.
B. If the columns of an m×n matrix A are orthonormal, then the
linear mapping x→Ax preserves lengths.
C. If a set S={u1,...,up} has the property that ui⋅uj=0 whenever
i≠j, then S is an orthonormal set.
D. Not every orthogonal set in Rn is a linearly independent
set.
E. An orthogonal matrix is invertible.