## Introduction of co-ordinate Geometry

First it was studied by French Mathematician Rene Descartes in 1637. In this geometry , position of the points is denoted by some special numbers we call them coordinates and we denote different shapes ( lines, circles etc ) with the help of algebraic equations. We use coordinates in this branch of mathematics, so we call it Co-ordinate geometry.

**Cartesian Coordinates:**

We draw two perpendicular lines in a plane, both are intersecting to each other at a point O, horizontal line is XOX’ and vertical line is YOY’, we call them ** Coordinate axes** or

**or**

*Rectangular coordinate axes***.**

*rectangular axes*Line XOX’ is known as ** x-axes** and line YOY’ is known as

**and intersecting point is O, we call it**

*y-axes***.**

*origin*Let there is a point P in a plane, draw two perpendiculars from point P to x and y axes. Which are PM and PN ( shown in the below figure ), we denote the distance of P point from x-axes is x and from y-axes is y. we call x as ** x-coordinate or abscissa** and y as

**of point P. and these x and y are the coordinates of the Point P. we write them like (x,y).**

*y-coordinate or ordinate***Quadrant and sign of coordinates:**

Coordinate axes divides the plane into four parts, these four parts are XOY, YOX’, X’OY’ and Y’OX. We call them first, second, third and fourth quadrant.

From the right and upper side of the origin all distances are positive on OX and on OY and at left and down side from the origin all distances are negative on OX’ and on OY’.