so easy let me teach you. cos⁶x = (cos²x)³ = [(1 + cos2x)/2]³ = (1/8)(1 + cos2x)³ = (1/8)(1 + 3cos2x + 3cos²2x + cos³2x) = 1/8 + (3/8)cos2x + (3/8)cos²2x + ...
確定！ 回上一頁
