A:2:3
B:3:2
C:8:12
D:4:9
On May 22, a Han taxi driver an old lady to the hospital as soon as he could in Xinjiang.
如图,直线a,b被直线c所截,若a∥b,∠1=110°,则∠2等于( )
同纬度甲乙两地海拔分别是720米和1720米,甲地气温28.8℃,乙地气温为( )。
(Ⅰ)求证:AB∥EF;
(Ⅱ)若PA=PD=AD,且平面PAD⊥平面ABCD,求平面PAF与平面AFE所成的锐二面角的余弦值.