回復 1# bugmens 的帖子
\(\int_{\frac{3}{2}}^{0}{\left[ 4\sin \theta +\left( 6-4\theta \right)\cos \theta \right]}d\left( 4\cos \theta -\left( 6-4\theta \right)\sin \theta \right)-\int_{\frac{3}{2}}^{0}{4\sin \theta d\left( 4\cos \theta \right)=9}\)
所求\(=9\times 2+\frac{1}{2}\times {{6}^{2}}\pi =18\pi +18\)
