题目内容
计算：
=______．
| cos15°+sin15° |
| cos15°-sin15° |
∵
=
=
=
=
=
．
故答案为：
．
| cos15°+sin15° |
| cos15°-sin15° |
=
| (sin15°+cos15°)2 |
| (cos15°-sin15°)(cos15°+sin15°) |
=
| 1+2sin15°cos15° |
| cos215°-sin215° |
=
| 1+sin30° |
| cos30° |
=
1+
| ||||
|
=
| 3 |
故答案为：
| 3 |
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计算cos45°cos15°-sin45°cos75°的结果是（ ）
A、
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B、
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C、
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| D、1 |