挑战习题
1/5单选题
难度:

1.

如图,两建筑物AB和CD的水平距离为30米,从A点测得D点的俯角为30°,测得C点的俯角为60°,则建筑物CD的高为(      )米



A

203 

B

10

C

15

D

5

提示1:
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
正确答案:QQ==
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