sin (2x) = 2sin(x)cos(x) cos(2x) = cos 2 (x) – sin2 (x) = 1 – 2sin 2 (x) = 2cos 2 (x) – 1 tan(2x) = [2 tan(x)] / [1 - tan 2 (x)]
確定! 回上一頁