三角比的延伸定義 | General Definitions of Trigonometric Ratios

影片內容：

01:32 – 旋轉角與象限 | angles of rotation and quadrants
05:45 – 同界角 | coterminal angles
07:38 – 任何角度的三角比 | trigonometric ratios of any angle
16:09 – 特殊角的三角比 (利用單位圓解釋) | trigonometric ratios of special angles (explained with unit circle)