These comprehensive RBSE Class 9 Maths Notes Chapter 3 Coordinate Geometry will give a brief overview of all the concepts.

## RBSE Class 9 Maths Chapter 3 Notes Coordinate Geometry

1. Coordinate Geometry : In this Geometry the position of a point is represented by specific numbers, which we call coordinates and different figures (lines, curves etc.) formed by them are represented by algebraic equations. Thus this branch of Geometry has developed by mixture of geometry and algebra. Therefore on account of the use of coordinates this branch of Mathmatics is called Coordinate Geometry.

2. Cartesian Coordinates : Let XOX and YOY’ be two mutually perpendicular lines in any plane which intersect at the point O. These are called Coordinate axes and O is called the origin. XOX and YOY’ are mutually perpendicular, so XOX’ and YOY are called right angular axes and rectangular coordinate axes.

3. y-coordinate of each point lying on x-axis is 0.

4. x-coordinate of each point lying on y-axis is 0.

5. Signs of Coordinates in Quadrants : If the coordinates of any point P in the plane be (x, y), then

In first quadrant, x > 0, y > 0 ; coordinates (+, +)

In second quadrant, x < 0, y > 0 ; coordinates (-, +)

In third quadrantx, < 0, y < 0 ; coordinates (-, -)

In fourth quadrant, x > 0, y < 0 ; coordinates (+, -)

coordinates this branch of Mathmatics is called Coordinate Geometry.

6. To Be Remembered :

(i) If the coordinates of any point P are (x, y), then we write it P(x, y).

(ii) The abscissa of any point is the perpendicular distance of that point from y-axis.

(iii) The ordinate of any point is the perpendicular distance of that point from x-axis.

(iv) The abscissa of any point is positive on the right side of y-axis and negative on the left side.

(v) The ordinate of any point is positive above x-axis and negative below x-axis.

(vi) If y = 0, then the point lies on x-axis.

(vii) If x = 0, then the point lies on y-axis.

(viii) If x = 0, y = 0, then point is origin.

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