题目内容
| sin40°(1+2cos40°) |
| 2cos240°+cos40°-1 |
原式=
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| sin40°+2sin40°cos40° |
| (2cos240°-1)+cos40° |
| sin40°+sin80° |
| cos40°+cos80° |
| sin(60°-20°)+sin(60°+20°) |
| cos(60°-20°)+cos(60°+20°) |
| 2sin60° |
| 2cos60° |
| 3 |
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