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问题 解答题
已知双曲线
x2
9
-
y2
16
=1．
（1）求焦点F1，F2的坐标；并求出焦点F2到渐近线的距离；
（2）若P为双曲线上的点且∠F1PF2=30°，求△F1PF2的面积S．
答案

（1）由题意得：a2=9，b2=16，

∴c=5，

焦点F1，F2的坐标：F1（-5，0），F2（5，0）；

焦点F2到渐近线：y=

4
3
x的距离：d=
20
5
=4；

（2）设|PF1|=m，|PF2|=n由题知：m-n=6①

m2+n2-

3
mn=100②

由①②得(m-n)2+(2-

3
)mn=100

所以   mn=

64
2-
3
=64(2+
3
)

所以   S=

1
2
mnsin300=16(2+
3
)

单项选择题 B1型题

正畸的最终目标是将牙列矫正为（）

A.错

B.早接触

C.干扰

D.平衡

E.个体正常
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改错题

短文改错：

下面短文中有10处语法错误。请在有错误的地方增加、删除或修改某个单词。

增加：在缺词处加一个漏字符号（∧）,并在其下面写上该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写上修改后的词。

注意：①每处错误及其修改均仅限一词；

②只允许修改10处，多者（从11处起）不计分。

Did you enjoy yourself yesterday? I suppose you did. But I’d like to tell you how a bad day I had yesterday. Nothing just went wrong. In the morning, my alarm clock didn’t ring, so I woke up an hour late. I was in such hurry that I burnt my hand when I was cooking the breakfast. Then I ran out of the house to catch the 8:30 buses. This is the bus I usually take. But, you may laugh, I missed it of course. I am very unhappy and scared as well because teacher hates the students coming late to school. So I ran three miles to school only to discover that nobody was there. The school was quiet but peaceful. Our classroom was locking. I realized in that moment: It was Sunday.
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