Past exam of the mathematics course of the University of Cambridge 2003 iii Paper 26 5 b Solution Created 2026-10-03 Updated 2026-10-14
Identify the ambient Euclidean space with and let be multiplication by . Equivalently, in real coordinates,This linear map preserves the norm and satisfies . On the unit sphere defineIt is continuous, tangent because it lies in , and has norm one everywhere. It is therefore a nowhere-zero section of the tangent bundle, including when and the sphere is . This supplies a nonvanishing tangent field on an odd-dimensional sphere explicitly.