設(shè)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033136951546.png)
的內(nèi)角
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033136966517.png)
所對邊的長分別為
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033136982447.png)
,若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033136997923.png)
,則角
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033137013312.png)
= ( )
試題分析:由正弦定理
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033137107494.png)
,而
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033137122762.png)
,令
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033137138663.png)
,則由余弦定理
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033137153865.png)
,得
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033137169874.png)
,解得
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033137263625.png)
,所以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033137278616.png)
,故先A.
練習冊系列答案
相關(guān)習題
科目:高中數(shù)學
來源:不詳
題型:解答題
在
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958523543.png)
中,角
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958538297.png)
、
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958554310.png)
、
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958569313.png)
的對邊分別為
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958585278.png)
、
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958601299.png)
、
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958616237.png)
.設(shè)向量
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958647573.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958663749.png)
.
(1)若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958679469.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958710456.png)
,求角
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958538297.png)
;(2)若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958741740.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958772599.png)
,求
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033958788440.png)
的值.
查看答案和解析>>
科目:高中數(shù)學
來源:不詳
題型:解答題
已知
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824031143829523.png)
中,角
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824031143845502.png)
的對邊分別為
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824031143860444.png)
,且滿足
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824031143876874.png)
.
(I)求角
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824031143892309.png)
的大�。�
(Ⅱ)設(shè)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824031143907930.png)
,求
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824031143923479.png)
的最小值.
查看答案和解析>>
科目:高中數(shù)學
來源:不詳
題型:填空題
類比正弦定理,如圖,在三棱柱
ABC-A1B1C1中,二面角
B-AA1-C,
C-BB1-A,
B-CC1-A的平面角分別為
α,
β,
γ,則有________.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240343533032323.jpg)
查看答案和解析>>
科目:高中數(shù)學
來源:不詳
題型:填空題
已知
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033630761278.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033630777299.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033630793237.png)
分別是
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033630808544.png)
的三個內(nèi)角
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033630824300.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033630839309.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033630871313.png)
所對的邊,若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033630886449.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033630902453.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824033630917479.png)
,則
.
查看答案和解析>>
科目:高中數(shù)學
來源:不詳
題型:單選題
在
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824032724043319.png)
ABC中,若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824032724058373.png)
、
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824032724074370.png)
的對邊長分別為b、c,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824032724090556.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824032724105466.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824032724105604.png)
,則
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824032724121389.png)
( )
查看答案和解析>>