如图所示，某办公大楼正前方有一根高度是15米的旗杆ED，从办公楼顶端A测得旗杆顶端E的俯角α是45°，旗杆底端D到大楼前梯坎底边的距离DC是20米，梯坎坡长BC是12米，梯坎坡度i=1： $\sqrt{3}$ ，则大楼AB的高度约为（　　）（精确到0.1米，参考数据： $\sqrt{2}$ ≈1.41， $\sqrt{3}$ ≈1.73， $\sqrt{6}$ ≈2.45）

    There are many different greeting customs around the world. Here are some.

    Chile(智利) People usually shake hands when they meet for the first time. When two women fist meet, they sometimes give one kiss on the cheek. They actually “kiss the air'' Women also greet both male and female friends with a kiss. Chilean men give their friends warm abrazos (hugs) or sometimes kiss women on the cheek.

    Finland (芬兰)Finns greet each other with a firm handshake. Hugs and kisses are only for close friends and family.

    Korea (韩国) Men bow slightly and shake hands to greet each other. Women do not usually shake hands. To address someone with his or her full name, the family name comes first, the first name.

    The United States (美国) People shake hands when they are first introduced. Friends and family member often hug or kiss on the cheek when they see each other. In these situations, men often kiss women but not other men.