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求值:
cos20°
cos35°
1-sin20°
= ___ .
人气:218 ℃ 时间:2020-05-11 14:59:53
解答
cos20°
cos35°
1-sin20°
=
cos210°-sin210
cos(45°-10°)(cos10°-sin10°)
=
cos10°+sin10°
cos45°cos10°+sin45°sin10°
=
1
2
2
=
2

故答案为
2
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