Which best describes the polygon whose vertices in the coordinate plane are (-5, 5), (0, 5), (0, 0), (-5, 0?

For 4 and 5, the easiest way is to actually plot these out on a graph you make on a piece of paper. As long as you know what equilateral (same length sides), equiangular (all the same angles), and regular (both) mean, you should be able to measure.