Line 1= undefined Line 2= -4/3 Line 3= 4/3 Line 4= undefined Line 5= 7/3 Line 6= -7/3 Line 7=no slope Line 8=no slope Line 9 =undefined Line 10 = undefined Line 11 = no slope Line 12= undefined
NOTE: if the line is horizontal it have a zero slope or no slope and a vertical line the slope is undefined.
