This is LaTeX code:
[latex]
P_{AB}= ( \frac{x_A+x_B}{2},\frac{y_A+y_B}{2}), P_{BC}= ( \frac{x_B+x_C}{2},\frac{y_B+y_C}{2}), P_{AC}= ( \frac{x_A+x_C}{2},\frac{y_A+y_C}{2})
[/latex]