From the previous problem, $\sigma^{\prime}=\varepsilon_{0} \frac{\varepsilon-1}{\varepsilon} E_{0} \cos \theta$
(a) Then $\oint \quad \vec{E} \cdot \overrightarrow{d S}=\frac{1}{\varepsilon_{0}} Q=\pi R^{2} E_{0} \cos \theta \frac{\varepsilon-1}{\varepsilon}$
(b) $\oint \vec{D} \cdot \overrightarrow{d l}=\left(D_{1 t}-D_{2 t}\right) l=\left(\varepsilon_{0} E_{0} \sin \theta-\varepsilon \varepsilon_{0} E_{0} \sin \theta\right)=-(\varepsilon-1) \varepsilon_{0} E_{0} l \sin \theta$