How Do You Know If Vectors Are Orthonormal?

How Do You Know If Vectors Are Orthonormal? Definition. A set of vectors S is orthonormal if every vector in S has magnitude 1 and the set of vectors are mutually orthogonal. The set of vectors { u1, u2, u3} is orthonormal. Proposition An orthogonal set of non-zero vectors is linearly independent. Are vectors orthonormal?