2006-II-50

12-06-2023 app.cch 尚無留言

答案：A
留意圓心的坐標

$\begin{array}{cl} = & (\frac{- (- 4)}{2}, \frac{- (6)}{2}) \\ = & (2, - 3) \end{array}$

所以，通過 $(1, 2)$ 的直徑的斜率

$\begin{array}{cl} = & \frac{- 3 - 2}{2 - 1} \\ = & - 5 \end{array}$