【单选题】Why did the agent take a picture of one of the women at the brief moment she faced his direction?
A.
because he knew one of the two women and wanted to take a picture of her.
B.
because that was one of the few exciting things in his job.
C.
because he was well-trained as a secret agent.
D.
because he was so bored and wanted to entertain himself.
【简答题】如图,在△ABC中,∠C=90°,D是BC边上任意一点,DE垂直平分AB,垂足为E,且DE=DC. (1)求∠B的度数; (2)若CD=3,求AB的长.
【单选题】Mrs. Nelson asked a difficult queation and looked at David. She thought he was ______ to know the answer.
【简答题】如图,在△ABC中,D是BC边上的任意一点,AH⊥BC于H,图中以AH为高的三角形的个数为( )个。
【简答题】附加题:已知:如图,点O是等腰直角△ABC斜边AB的中点,D为BC边上任意一点. 操作:在图12中作OE⊥OD交AC于E,连接DE. 探究OD、BD、CD三条线段之间有何等量关系?请探究说明.
【多选题】中国革命主要就是打击两个敌人,它们分别是( )。
【简答题】在 △ABC中,D是BC边上任意一点(D与B,C不重合),且 = + .求证:△ABC为等腰三角形.
【单选题】如图,已知:在△ABC中,AB=AC,D是BC边上任意一点,DF⊥AC于点F,E在AB边上,ED⊥BC于D,∠AED=155°,则∠EDF等于 [ ]
【简答题】在△ABC中,∠A= π 6 ,D是BC边上任意一点(D与B、C不重合),且丨 AB | 2 = | AD | 2 + BD ? DC ,则∠B=______.