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research:memos:mathematics:2d_notes [2017/12/18 02:13] – kobayash | research:memos:mathematics:2d_notes [2017/12/18 04:52] (現在) – kobayash | ||
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\end{align} | \end{align} | ||
+ | ==== A line between two points ==== | ||
+ | \begin{align} | ||
+ | \left\{ | ||
+ | \begin{array}{l} | ||
+ | y_1 = ax_1+b \\ | ||
+ | y_2 = ax_2+b | ||
+ | \end{array} | ||
+ | \right. | ||
+ | \end{align} | ||
+ | If $x_1 \ne x_2$, | ||
+ | \begin{align} | ||
+ | \left\{ | ||
+ | \begin{array}{l} | ||
+ | a=\dfrac{y_2-y_1}{x_2-x_1}\\ | ||
+ | b=\dfrac{x_2y_1-x_1y_2}{x_2-x_1} | ||
+ | \end{array} | ||
+ | \right. | ||
+ | \end{align} | ||