Plot and interpret points in all four quadrants, including points on the axes and with negative coordinates, and calculate horizontal and vertical distances, midpoints, and missing endpoints using coordinate relationships. Calculate and interpret positive, negative, zero, and undefined slopes, determine whether lines are parallel, and write equations of lines from a slope and y-intercept or from two points. Use coordinate methods to solve geometric problems involving collinearity, lengths, areas, and properties of triangles and quadrilaterals.