题干

在学习了解直角三角形的有关知识后,一学习小组到操场测量学校旗杆的高度.如图,在测点D处安置测倾器,测得旗杆顶的仰角∠ACE的大小为30°,量得仪器的高CD为1.5米,测点D到旗杆的水平距离BD为18米,请你根据上述数据计算旗杆AB的高度(结果精确到0.1米;参考数据 3 ≈1.73).
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答案(点此获取答案解析)

解:在Rt△ACE中,∠ACE=30°,CE=BD=18,
∴tan∠ACE=
A
E
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E

同类题2

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

    Tired of traditional running? Well, maybe it's time to try using your hands instead. That's what Shaun McCarty and other Australians are doing — running on all fours. ____

    McCarthy, who comes from Melbourne, Australia, said he's the one behind the term “crunning.” “It's not crawling, it's not running.” he said. “Crunning is a better workout than running. It puts more of an emphasis(着重)on the body than traditional running does. ____ ”

    McCarthy thinks that he gets much more exhausted after crunning, so he believes it must burn more calories than running.

     ____ Some believe crunning could result in bad shoulder injuries or broken noses.

    But McCarthy is not worried. Many Melbourne residents have been seen running around on all fours. ____ In the Chinese city of Zhengzhou, crawling, a much slower version of crunning, has been a favourite activity for many years. According to some people there, the exercise is believed to date back two thousand years to the Han Dynasty.

     ____ Then McCarthy advises you to buy some good shoes, hand gloves and most important of all, a face mask!

A. Ready to give crunning a try?

B. As it turns out, they are not the only ones.

C. Crunning seems more difficult than traditional running.

D. It really exercises your legs and shoulders at the same time.

E. It's part of the Internet's latest fitness activities: “Crunning.”

F. However, many are not sure if it is the right exercise for humans.

G. He warns, however, that he can't say whether crunning is potentially harmful.