$ 解：(1)由题意，可得圆锥的母线SA=\sqrt{AO^2+SO^2}=40(\ \mathrm {cm})$
$ 圆锥的侧面展开扇形的弧长l=2\pi \cdot OA=20\pi\ \mathrm {cm}$
$ \therefore S_{侧}=\dfrac{1}{2}L\cdot SA=400\pi\ \mathrm {cm^2}$
$ S_{圆}=\pi AO^2=100\pi\ \mathrm {cm^2}，$
$ \therefore S_{全}=S_{圆}+S_{底}=(400+100)\pi =500\pi (\ \mathrm {cm^2}).$
$ (2)（更多请点击查看作业精灵详解）$
