# Coordinate Geometry Class 9 Notes Mathematics Chapter 3

#### Lesson at a Glance

1. The location of an object in a plane is found by drawing two perpendicular lines. One of them is horizontal and other one is vertical.

2. The plane is called the cartesian plane and the lines are called the coordinate axes.

3. The horizontal and vertical lines are called x-axis and y-axis respectively.

4. The point of intersection of the x-axis and y-axis is called the origin.

5. The coordinate axes divide the cartesian plane into four parts which are called quadrants.

7. The distance of a point from y-axis is called itsx-coordinate.

8. The distance of a point from x-axis is called y-coordinate.

9. The x-coordinate is also called abscissa and the y-coordinate is also called ordinate.

10. The cartesian plane is also called the coordinate plane orthe xy-plane.

11. If x-coordinate of a point is α and y-coordinate is β, then(α, β) are called the coordinates of the point.

12. The coordinates of a point on the x-axis are of the form(α, 0) and that of the point on the y-axis are (0, β).

13. The coordinates of the origin are (0, 0).

14. If (x1, y1) = (x2, y2), then x1 = x2 and y1 = y2 and if (x1, y1)≠ (x2, y2), then x1 ≠ x2 and y1 ≠ y2.

15. The signs of x-coordinate and y-coordinate of a point in the quadrants are as follows:

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