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Sin²1°+ Sin²2°+…＋ Sin²69°＝?

分类: 作业答案 • 2022-01-09 18:02:45

问题描述：

Sin²1°+ Sin²2°+…＋ Sin²69°＝?
最后是69度不是89°
错了最后是89°不是69°，是我们老师抄错了。汗死

答

Sin²1°+ Sin²2°+…＋ Sin²89°
=(sin²1°+cos²1°)+(sin²2°+cos²2°)+.+(sin²44+cos²46)+sin²45°
=1*44+1/2
=44.5

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Sin²1°+ Sin²2°+…＋ Sin²69°＝?

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