Coordinate Geometry

The x-coordinate (abscissa) is the distance of a point from the y-axis.

The y-coordinate (ordinate) is the distance of a point from the x-axis.

Coordinates of a point on the x-axis: (x, 0)

Coordinates of a point on the y-axis: (0, y)

PQ = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}

PQ = \sqrt{(x_1 - x_2)^2 + (y_1 - y_2)^2}

OP = \sqrt{x^2 + y^2}