Class 9 Maths Chapter 3 Coordinate Geometry
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.
QUADRANT I (+,+) Example(3,4)
QUADRANT II- (-,+)Example(-6,2)
QUADRANT III- (-,-)Example(-3,-5)
QUADRANT IV- (+,-)Example(3,-1)
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.
