In this video we will learn about the Cartesian System of Geometry in which the coordinate plane is divided by the x and y axis.

A **Cartesian system** is the one which specifies a point plotted uniquely on a plane by a pair of numerical coordinates, having a pre-defined distance from the two fixed perpendicular coordinates, measured in the same unit of length.

- The numbers are represented on a number line on which the points are marked at equal distances.
- Two number lines are taken and intersected perpendicularly at the point zero also called the origin.
- The numbers on the right side of the horizontal number line, also x- axis, are positive and that on the left side are negative.
- The numbers to the top of the origin of the vertical number line, also y-axis, are positive and that below the origin are negative.
- The x- axis and the y-axis divide the coordinate plane into four parts called the quadrant.
- The quadrants are named in an anti-clockwise order, starting with I, II, III and IV.

- In the first quadrant both the x and y coordinates are positive
- In the second quadrant x coordinate is negative and the y coordinate is positive
- In the third quadrant both x and y coordinates are negative, and
- In fourth quadrant x coordinate is positive and the y coordinate is negative.

- Any point can be depicted on the coordinate plane by specifying its perpendicular distances from the x and y coordinates.

**CBSE Class 9th Quadrilaterals - Introduction and Types of Quadrilaterals**