题目内容
计算cos30°+![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_ST/0.png)
A.
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_ST/1.png)
B.
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_ST/2.png)
C.
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_ST/3.png)
D.
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_ST/4.png)
【答案】分析:根据特殊角的三角函数就可以解决.
解答:解:原式=
+
×![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/2.png)
=
+1
=
.
故选D.
点评:解答此题要熟记三角函数值:
sin30°=
,sin45°=
,sin60°=
;
cos30°=
,cos45°=
,cos60°=
;
tan30°=
,tan45°=1,tan60°=
;
ctan30°=
,ctan45°=1,ctan60°=
.
解答:解:原式=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/0.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/1.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/2.png)
=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/3.png)
=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/4.png)
故选D.
点评:解答此题要熟记三角函数值:
sin30°=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/5.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/6.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/7.png)
cos30°=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/8.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/9.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/10.png)
tan30°=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/11.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/12.png)
ctan30°=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/13.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131211103311252052692/SYS201312111033112520526000_DA/14.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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