Reflection (In x-axis, y-axis, x = a, y = a and the origin; Invariant Points)
294. Coordinates & Axes · Finding your place on the plane
P's coordinates match its distance from the axes.
A point's coordinates measure its perpendicular distances from the axes — the x-coordinate from the y-axis and the y-coordinate from the x-axis, each signed by direction. Together they pin the point exactly.