# CBSE Notes for Class 9 Maths Chapter 3 Coordinate Geometry

## Class 9 Maths Chapter 3 Coordinate Geometry

Coordinate Geometry is one of the most critical chapters of Class 9 mathematics. Geometry as a branch of mathematics is used in various ways in daily life. The coordinate system introduced in the chapter will help you better understand your higher classes. GharPeShiksha provides its students with the best Revision Notes, NCERT solutions, NCERT Exemplar Solutions, Previous Year Questions of this Chapter, Formulae Sheet, Model Answer Sheets designed by its expert teachers. The study material is updated each year as per the requirements and is consistent with the new syllabus. It is an exclusive feature that the students can enjoy at GharPeShiksha only.

What is Coordinate geometry?
A coordinate geometry can be defined as a branch of geometry, where the position of the points on the plane is defined with the help of an ordered pair of numbers known as coordinates.

Applications of Coordinate Geometry
Coordinate Geometry is mainly used for:
Calculating the distance between the two given points.
To describe the equations of different geometric figures.
Finding the equation, midpoint, or slope of a line segment.
For calculating the area and the perimeter of a given polygon.
To conclude the given set of lines are parallel or perpendicular.

Cartesian system
It consists of two perpendicular lines: one is horizontal and other one is vertical.
The horizontal line is called X-axis and the vertical line is called Y-axis. The point of intersection where these two lines meet is called origin and it is denoted by O.

NOTE: X’OX is called X-axis
YOY’ is called Y-axis.
The two axes (X & Y) divides the Cartesian plane( or XY Plane) into four quadrants I,II,III & IV.

Coordinates: (x, y)
Here, x coordinate is called Abscissa
y coordinate is called Ordinate
For example: Locate points (5, 0), (0, 5), (5, 2), (-3, 5), (-3, -5) and (5, -3) in the Cartesian plane.
Plot the points (−2,4)(−2,4), (3,3)(3,3), and (0,−3)(0,−3) in the coordinate plane.