Given points $A(1,1), B(13,9),$ and $C(3,7) . \quad D$ is the midpoint of $\overline{A B},$ and $E$ is the midpoint of $\overline{A C}$ .
a. Find the coordinates of $D$ and $E$
b. Use slopes to show that $\overline{D E} \| \overline{B C}.$
c. Use the distance formula to show that $D E=\frac{1}{2} B C .$