trigo. Q.

As follows~~~


圖片參考：http://i182.photobucket.com/albums/x4/A_Hepburn_1990/A_Hepburn08Feb231609.jpg?t=1203754204


2008-02-23 23:40:32 補充：
凡是cosx = 0的general solution，都是π/2的單數倍數。即π/2, 3π/2, 5π/2 等。所以所出的solution: 7x = nπ π/2, 而n為任何整數的話，那麼general solution 一定是出π/2 的單數倍數。因為nπ π/2 = (2n 1)π/2 ，n為任何整數，general solution一定是π/2的單數倍數。

2008-02-23 23:42:29 補充：
7x = nπ+π/2nπ+π/2 = (2n+1)π/2全部漏了加號。