回答下列问题:
写出下列物质的电离方程式:
H2SO4 ____ Ba(OH)2 ____ Na2SO4 ____
Dolly is a middle school girl. Her parents want to take her to Ice and Snow Festival. How much will they pay for the tickets?
(Ⅰ)求证:AB⊥平面SAC
(Ⅱ)若SA=2AB=3AC,求二面角S﹣BD﹣A的余弦值.