# Vector identity

## Homework Statement

I am to show: closed integral {phi (grad phi)} X (n^)dS=0

## The Attempt at a Solution

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Dick
Homework Helper
Is 'X' supposed to mean a cross product between the normal vector and the gradient?

yes.It means that.

Dick
Try using $$\int_S n \times a dS = \int_V curl(a) dV$$.