好题，利用sin2x=2sinxcosx, 应该可以凑出答案，我手边没有纸笔，心算得34.25, 可能不准

来源: monseigneur 于 2022-01-22 16:19:30 [旧帖] [给我悄悄话] 本文已被阅读：次

WENXUECITY.COM does not represent or guarantee the truthfulness, accuracy, or reliability of any of communications posted by other users.