题目内容
（易诱导公式）sin(-
)+2sin
+3sin
等于（ ）
| π |
| 3 |
| 4π |
| 3 |
| 2π |
| 3 |
| A、1 | ||||
B、
| ||||
| C、0 | ||||
| D、-1 |
分析：运用诱导公式可知sin(-
)+2sin
+3sin
=-sin
+2sin(π+
)+3sin(π-
)，进而化简整理根据
这个特殊角求得答案．
| π |
| 3 |
| 4π |
| 3 |
| 2π |
| 3 |
| π |
| 3 |
| π |
| 3 |
| π |
| 3 |
| π |
| 3 |
解答：解：sin(-
)+2sin
+3sin
=-sin
+2sin(π+
)+3sin(π-
)=-sin
-2sin
+3sin
=0
故选D
| π |
| 3 |
| 4π |
| 3 |
| 2π |
| 3 |
| π |
| 3 |
| π |
| 3 |
| π |
| 3 |
| π |
| 3 |
| π |
| 3 |
| π |
| 3 |
故选D
点评：本题主要考查了用诱导公式化简求值的问题．解题的时候要注意对三角函数正负值的判定．
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