# An easy vector identity I can't prove

1. Mar 23, 2012

### nathangrand

Show the following, where U is a vector, and r is the position vector: $\nabla$(U.r) = U in polar coordinates

Many Thanks

2. Mar 23, 2012

### sunjin09

A quick mechanical check shows it is not right

3. Mar 23, 2012

### xaos

assuming, "find U such that...", i would start with the basis vectors.