$$\text{a.}\;\;\;E = \bigg\lbrace (r, \theta, z)|0 \le \theta \le \pi, 0 \le r \le 4sen\theta, 0 \le z \le \sqrt{16-r^2}\bigg\rbrace$$ $$\text{b.}\;\;\;\int_0^{\pi}\int_0^{sen\theta}\int_0^{\sqrt{16-r^2}} f(r, \theta, z)rdzdrd\theta$$