## Coordinate Geometry - ESSENTIAL POINTS

• Two perpendicular linesare required to locate the position of an object or a point in a plane. One of them is horizontal, and the other is vertical.
• The plane is called the Cartesian, or coordinate plane and the lines are called the coordinate axes.
• In the Cartesian plane, the horizontal line is called the x -axis, and the vertical line is called the y - axis.
• The coordinate axes divide the plane into four parts called quadrants.
• The point of intersection of the axes is called the origin.
• The distance of a point from the y - axis is called its x-coordinate, or abscissa, and the distance of the point from the x-axis is called its y-coordinate, or ordinate.
• If the abscissa of a point is x and the ordinate is y, then (x, y) are called the coordinates of the point.
• The coordinates of a point on the x-axis are of the form (x, 0) and that of the point on the y-axis are (0, y).
• The coordinates of the origin are (0, 0).
• The coordinates of a point are (+ , +) in the first quadrant, (–, +) in the second quadrant, (–, –) in the third quadrant and (+, –) in the fourth quadrant.
• If x ≠ y, then (x, y) ≠ (y, x), and (x, y) = (y, x), if x = y.