题目内容
求值：
①
②
-
．
①
| sin47°-sin17°cos30° |
| cos17° |
②
| 1 |
| sin10° |
| ||
| cos10° |
①式子=
=
=sin30°=
；
②式子=
=
=
=4．
| sin(17°+30°)-sin17°cos30° |
| cos17° |
| cos17°sin30° |
| cos17° |
| 1 |
| 2 |
②式子=
cos10°-
| ||
| sin10°cos10° |
2(
| ||||||
|
| 2sin20° | ||
|
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