Key Points - Coordinate Geometry

1. Cartesian System
2. Plotting a Point in the Plane with given Coordinates

- Coordinate Geometry: The branch of mathematics in which geometric problems are solved through algebra by using the coordinate system is known as coordinate geometry.
- Coordinate System: Coordinate axes: The position of a point in a plane is determined with reference to two fixed mutually perpendicular lines. called the coordinate axes.
In this system. position of a point is described by ordered pair of two numbers.
- Ordered pair: A pair of numbers a and b listed in a specific order with 'a' at the first place and 'b' at the second place is called an ordered pair (a.b)
Note that (a. b) ≠ (b. a)
Thus (2.3) is one ordered pair and (3.2) is another ordered pair.
In given figure O is called origin.
The horizontal line X1
OX is called the X-axis.
The vertical line YOY' is called the Y-axis.

P(a.b) be any point in the plane. 'a' the first number denotes the distance of point from Y-axis and 'b' the second number denotes the distance of point from X-axis. a - X - coordinate | abscissa of P. b - Y - coordinate | ordinate of P.
The coordinates of origin are (0.0)
Every point on the x-axis is at a distance o unit from the X-axis. So its ordinate is 0.
Every point on the y-axis is at a distance of unit from the Y-axis. So. its abscissa is 0.
Note: Any point lying on X − axis or Y − axis Y-axis does not lie in any quadrant.