6.
(a)
The slope for the side AB is:
[tex]\begin{gathered} A=(-5,-4)=(x1,y1) \\ B=(5,-2)=(x2,y2) \\ m_{AB}=\frac{y2-y1}{x2-x1}=\frac{-2-(-4)}{5-(-5)}=\frac{2}{10}=\frac{1}{5}=0.2 \end{gathered}[/tex]The slope for the side BC is:
[tex]\begin{gathered} B=(5,-2)=(x1,y1) \\ C=(7,6)=(x2,y2) \\ m_{BC}=\frac{6-(-2)}{7-5}=\frac{8}{2}=4 \end{gathered}[/tex]The slope for the side DC is:
[tex]\begin{gathered} D=(-3,4)=(x1,y1) \\ C=(7,6)=(x2,y2) \\ m_{DC}=\frac{y2-y1}{x2-x1}=\frac{6-4}{7-(-3)}=\frac{2}{10}=\frac{1}{5}=0.2 \end{gathered}[/tex]And the slope for AD is:
[tex]\begin{gathered} A=(-5,-4)=(x1,y1) \\ D=(-3,4)=(x2,y2) \\ m_{AD}=\frac{4-(-4)}{-3-(-5)}=\frac{8}{2}=4 \end{gathered}[/tex](b) According to the previous results:
[tex]\begin{gathered} m_{AB}=m_{DC} \\ so \\ m_{AB}\parallel m_{DC} \end{gathered}[/tex][tex]\begin{gathered} m_{BC}=m_{AD} \\ so\colon \\ m_{BC}\parallel m_{AD} \end{gathered}[/tex](c) Since it has two pairs of parallel sides, also, The opposite sides are of equal length, we can conclude that this figure is a parallelogram