【简答题】下面一组图形为三棱锥 P - ABC 的底面与三个侧面.已知 AB ⊥ BC , PA ⊥ AB , PA ⊥ AC . (1)在三棱锥 P - ABC 中,求证:平面 ABC ⊥平面 PAB ; (2)在三棱锥 P - ABC 中, M 是 PA 的中点,且 PA = BC =3, AB =4,求三棱锥 P - MBC 的体积.
【简答题】B. My secret for staying young is . Put all attention to the part of you---your brain and keep it young and growing. Keep your mind awake and you’ll stay young all over. These are exciting time....