题干

如图,从一张腰长为60cm,顶角为120°的等腰三角形铁皮OAB中剪出一个最大的扇形OCD,用此剪下的扇形铁皮围成一个圆锥的侧面(不计损耗),则该圆锥的高为(  )


A:10cm

B:15cm

C:10 3 cm

D:20 2 cm

上一题 下一题 0.0难度 选择题 更新时间:2019-01-22 01:09:32

答案(点此获取答案解析)

D

同类题2

                                                                                           小树

    张三带着斧头在树林里走过,一棵小树拦住他,对他说道:“把这些树木砍个干净吧,好心肠的朋友,我希望你砍掉它们!它们不让我自由发展,太阳光照不到我的身上;伸展我的根子吧,我又根本找不到地方;我的四周没有一点儿风的声音,这些树木在我头顶上结成了一个地道的罗网。我告诉你吧,要不是它们挡着我,要是我能自由生长,一年之内你就可以看到我成为这地方的光荣和骄傲,我的友爱的树阴将要一直遮庇到山谷的左右两边。然而,现在的情况却是如此,你瞧!我是灌木——就这么点儿高。”

    于是张三挥动着他的斧头,为朋友帮忙。他的好心肠没半点儿犹豫,他在小树的四周,开辟出了整整齐齐的一块地方。

    可怜的小树!它的胜利并没有存在多久,起初是炎热晒干了它的汁液,接着是挨到了大雨和冰雹的打击,最后,一场可怕的风暴,把它的枝叶吹折打落了。

    “愚蠢的东西,”小树听见附近有一条蛇说道,“你的毁灭是你自己招来的。如果你在树林的慈爱的荫庇下多栽培些日子,那么,无论炎热也好,大风也好,都不可能这样地逼上门来:你有老树保护你的安全。如果到了那些树木因为寿命已经结束,统统消失了的时候,这就轮到你一年年地成长,长到它们那样的高大,那时候你已经日积月累地锻炼得健壮有力,就不会有今日种种的祸害发生了。即使是再厉害点儿的风暴,你也经得住,也可以安然无恙。”

同类题3

任务型阅读

    Do you know what a big dream is? Does a big dream show one's future? Or, is a big dream something that provides only entertainment? Children dream big dreams, but there are three barriers to realizing dreams____

The self

    Immediately following the birth of a big dream, a negative self-talk takes over and gives all the reasons why it cannot happen. This voice inside of people is the ego(自我).It's there for protecting and should be listened to. Sometimes it is right, but more often it is wrong____ That's why only a handful of people make their dream come true

Family and friends

    Family and friends are a lot the ego.____ so they will often list all the reasons why the big dreams won't come true. Sometimes, family and friends destroy dreams of those they love most, out of their own fear of those left behind.

____

    If one gets past the first two barriers, one has to face the world. It is the last and the most terrible barrier. In the past, big dreamers were locked up and sometimes even killed when they were shown to the world. Fortunately, in most of the world today, big dreamers just get laughed at ____When children feel confident and then try their best, they will be ready to accept any failure. The truth is that every great dreamer whose dreams have never seen the light of success knows failure well. They simply fail until they succeed

A. The world

B. The future

C. Most people are influenced by it

D. They want to protect those they love

E. And their big dream is to be a rock star or a famous artist

F. They often kill them before they ever have a chance to grow

G. The way to realize a big dream is with confidence and action