x y. x y x y. ± = ±. ± = ±. ± = ∓. ∓. 2. 倍角公式. 2. 2. 2 sin(2 ) 2sin cos ... x x. = = − = −. = −. 3. 半角公式. 2. 3. 2. 3. 1 cos2. 3sin sin3 sin ( ).
確定！ 回上一頁
