Answer:
[tex](x_2,y_2) = (2x_m - x_1 ,2y_m - y_1 )[/tex]
Step-by-step explanation:
Given
[tex]\left(\frac{x_1+\:x_2}{2},\:\:\frac{y_{1\:}+y_2}{2}\right)\:=\:\left(x_m,\:y_m\right)[/tex]
Required
Determine x2, y2
Start by splitting the expression
[tex]x_m = \left(\frac{x_1+\:x_2}{2})[/tex] and [tex]y_m = (\frac{y_{1\:}+y_2}{2})[/tex]
Solving for x2 in [tex]x_m = \left(\frac{x_1+\:x_2}{2})[/tex]
Multiply through by 2
[tex]2 * x_m = \frac{x_1 + x_2}{2} * 2[/tex]
[tex]2x_m = x_1 + x_2[/tex]
Make x2 the subject;
[tex]x_2 = 2x_m - x_1[/tex]
Similarly:
[tex]y_m = (\frac{y_{1\:}+y_2}{2})[/tex]
Multiply through by 2
[tex]2 * y_m = \frac{y_1 + y_2}{2} * 2[/tex]
[tex]2y_m = y_1 + y_2[/tex]
Make y2 the subject;
[tex]y_2 = 2y_m - y_1[/tex]
Hence:
[tex](x_2,y_2) = (2x_m - x_1 ,2y_m - y_1 )[/tex]