R=\left\{(\rho, \phi, \theta) \in \mathbb{R}^{3} ; 0 \leq \r...

R=\left{(\rho, \phi, \theta) \in \mathbb{R}^{3} ; 0 \leq \rho \leq 3, 0 \leq \phi \leq \pi, 0 \leq \theta \leq 2 \pi}