CBSE Class 9 Mathematics Coordinate Geometry Notes Set A

CBSE Class 9 Concepts for Coordinate Geometry. Learning the important concepts is very important for every student to get better marks in examinations. The concepts should be clear which will help in faster learning. The attached concepts made as per NCERT and CBSE pattern will help the student to understand the chapter and score better marks in the examinations.

Chapter 3

Coordinate Geometry 

Points to Remember

Key Concepts

1. Two perpendicular number lines intersecting at point zero are called coordinate axes. The horizontal number line is the x-axis (denoted by X’OX) and the vertical one is the y-axis (denoted by Y’OY).

2. The point of intersection of x axis and y axis is called origin and denoted by ‘O’.

3. Cartesian plane is a plane obtained by putting the coordinate axes perpendicular to each other in the plane. It is also called coordinate plane or xy plane.

4. The x-coordinate of a point is its perpendicular distance from y axis.

5. The y-coordinate of a point is its perpendicular distance from x axis.

6. The point where the x axis and the y axis intersect is represented by coordinate points (0, 0) and is called the origin. It is denoted by ‘O’ on a Cartesian plane.

7. The abscissa of a point is the x-coordinate of the point.

8. The ordinate of a point is the y-coordinate of the point.

9. If the abscissa of a point is x and the ordinate of the point is y, then (x, y) are called the coordinates of the point.

10. The axes divide the Cartesian plane into four parts called the quadrants (one fourth part), numbered I, II, III and IV anticlockwise from OX.

11. The origin O has zero distance from both the axes.

12. The coordinate of a point on the x axis are of the form (x,0) and that of the point on y axis are (0,y)

13. Sign of coordinates depicts the quadrant in which it lies. The coordinates of a point are of the form (+, +) in the first quadrant, (-, +) in the second quadrant, (-,-) in the third quadrant and (+,-) in the fourth quadrant. 

14. To plot a point P (3, 4) in the Cartesian plane. Start from origin count 3 units on the positive x axis then move 4 units towards positive y axis and mark the point P.

15. If x ≠ y, then (x,y)≠(y,x) and if (x,y) = (y,x), then x=y.

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