first we move the reference point to the origin
we must move the other points to, the same unitis so -1 on x and -3 on y, so the new points are
[tex]\begin{gathered} (-5-1,2-3)\longrightarrow(-6,-1) \\ (-3-1,2-3)\longrightarrow(-4,-1) \\ (-1-1,1-3)\longrightarrow(-2,-2) \\ (-1-1,7-3)\longrightarrow(-2,4) \end{gathered}[/tex]
now to rotate 180 degrees we chang the sign of the two data on each point, so the new points are
[tex]\begin{gathered} (6,1) \\ (4,1) \\ (2,2) \\ (2,-4) \end{gathered}[/tex]
