Partial Derivatives of Metric vanish at Origin of Normal Neighborhood

Theorem
Let $\struct {M, g}$ be an $n$-dimensional Riemannian or pseudo-Riemannian manifold.

Let $U_p$ be the normal neighborhood for $p \in M$.

Let $\struct {U_p, \tuple {x^i}}$ be a normal coordinate chart.

Suppose $g_{ij}$ are the components of metric $g$ in coordinates $\tuple {x^i}$ at $p \in M$.

Then all partial derivatives of $g_{ij}$ vanish at $p$:


 * $\map {\dfrac {\partial g_{ij} }{\partial x^k} } {\map {x^r} p} = 0$