# NCERT Solutions Class 9 Maths Chapter 3 Coordinate Geometry

## Introduction:

In this chapter we will learn about Coordinate Geometry. keys point in this chapter.

- To locate the position of an object or a point in a plane, we required two perpendicular lines. One of them is horizontal, and the other is vertical.
- The plane is called the Cartesian, or coordinate plane and the line are called the coordinate axes.
- The horizontal line is called the x-axis, and the vertical line is called the y-axis.
- The coordinate axes divide the plane into four parts called quadrants.
- The point of intersection of the axes is called the origin.
- The distance of a point from the y-axis is called its x-coordinate, or abscissa, and the distance of the point from the x-axis is called its y-coordinate, or ordinate.
- If the abscissa of a point is x and the ordinate is y, then (x,y) are called the coordinates of the point.
- The coordinates of a point on the x-axis are of the form (x,0) and that of the point on the y-axis are (0,y).
- The coordinates of the origin are (0,0).
- The coordinates of a point are the form (+,+) in the first quadrant,(-,+) in the second quadrant (-,-) in the third quadrant and (+,-) in the fourth quadrant, where + denotes a positive real number and - denotes a negative real number.
- If x\(\displaystyle \ne \)y, then ( x,y ) \(\displaystyle \ne \) ( y,x ) , and ( x,y ) = ( y,x ), if x = y.

NCERT Class 9 Maths Chapter 5 Coordinate Geometry :

- NCERT Class 9 Maths Chapter 3 Coordinate Geometry Exercise 3.1
- NCERT Class 9 Maths Chapter 3 Coordinate Geometry Exercise 3.2

# NCERT Solutions Class 9 Maths Chapter 3 Coordinate Geometry Exercise 3.1

In this exercise-3.1 we will learn about Coordinate Geometry. You observed that the axes ( plural of the word axis' ) divide the plane into four part are called the quadrants ( one fourth part ), numbered I, II ,III and IV anticlockwise from OX. So, the plane consists of the axes and these quadrants. We call the plane, the Cartesian plane, or the coordinate plane, or the xy-plane. The axes are called the coordinate axes.

# NCERT Solutions Class 9 Maths Chapter 3 Coordinate Geometry Exercise 3.2

In this exercise-3.2 we will learn about Coordinate Geometry. The **horizontal** line X' X called the X-axis and the **vertical** line Y' Y is called the Y-axis. The point where X' X and Y' Y cross is called the **origin, **and is denoted by O. Since the positive numbers lie on the directions OX and OY , are called the positive directions of the x-axis and the y-axis, respectively. Similarly, OX' and OY' are called the negative directions of the x-axis and the y-axis, respectively. You see figure properly and read & learn 4 most important points in the exercise.

**(i)** If a point is in the 1st Quadrant, then the point will be in the form **( +,+ )** , since the 1st Quadrant is enclosed by the positive x-axis and the positive y-axis.

**(ii)** If a point is in the 2st Quadrant, then the point will be in the form **( -,+ )** , since the 2st Quadrant is enclosed by the negative x-axis and the positive y-axis.

**(iii)** If a point is in the 3st Quadrant, then the point will be in the form **( -,- )** , since the 3st Quadrant is enclosed by the negative x-axis and the negative y-axis.

**(iv)** If a point is in the 4st Quadrant, then the point will be in the form **( +,- )** , since the 4st Quadrant is enclosed by the positive x-axis and the negative y-axis.