Equation 3.1.2AAD3B6ABC9B1

\begin{equation} \int _{B(x,R)}f(y)\, \mathrm d y =\int _0^ R r^{d-1}\int _{S^{d-1}}f(x+r\omega )\, \mathrm d S(\omega )\, \mathrm d r \end{equation}