![](https://cache.ptt.cc/c/https/i.imgur.com/8H85Hkfl.jpg?e=1718730628&s=Ax1OCirtwsUpROLhgXWSmg)
推 j0958322080 : sinx*sinx = (1 - cos2x)/2, sin2xcos2x = 0.5sin4 04/26 10:56
→ j0958322080 : x 04/26 10:56
→ sweetdance : 抱歉有點不懂><! ><! 04/26 11:02
推 cuttlefish : 二倍角公式 還不懂去讀高中課本XD 04/26 11:17
→ sweetdance : 我去看看 哈哈 感謝 04/26 11:20
推 wayne2011 : 那裡看到Lagrange?你講的應該是"拉格朗日"乘數法... 05/01 11:12