Cosa+Cos2a+Cos3a+Cos4a+Cos5a+Cos6a+……+Cosna请回答的清楚些,
问题描述:
Cosa+Cos2a+Cos3a+Cos4a+Cos5a+Cos6a+……+Cosna
请回答的清楚些,
答
Cosa+Cos2a+Cos3a+Cos4a+Cos5a+Cos6a+……+Cosna
请回答的清楚些,