1) To locate the exact position of a point on a number line we need only a single reference.
2) To describe the exact position of a point on a Cartesian plane we need two references.
3) The two perpendicular lines taken in any direction are referred to as coordinate axes.
4) The horizontal line is called X – axis.
5) The vertical line is called Y – axis. 6) The meeting point of the axes is called the origin.
7) The distance of a point from Y – axis is called the x co-ordinate or abscissa.
8) The distance of a point from X-axis is called the y co-ordinate or ordinate.
9) The co-ordinates of origin are (0, 0),
10) The co-ordinate plane is divided into four quadrants namely Q ; Q , Q , Q i.e., first, second, third and fourth quadrants respectively.
11) The signs of co-ordinates of a point are as follows. Q (+, +); Q ; (-, +) Q (-, -); Q ; (+, -)
The coordinates of P are (1, – 2).
The coordinates of Q are (3, 4).
The coordinates of R are (- 2, – 5).
The co-ordinates of S are (- 4, 3).
