Coordinate Geometry: Cartesian Plane, Formulas and Examples

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Namrata Das

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The Cartesian coordinate system is a mathematical branch that describes how to represent a point in the n-dimensional coordinate plane in a unique way. Rene Descartes, a French philosopher and mathematician, proposed the Cartesian system theory in the 17th century. The link between Euclidean geometry and algebra was established by this Cartesian coordinate system, which revolutionized the study of mathematics. The Cartesian coordinate system is used to depict lines, curves, and geometric shapes in the n-dimensional plane and is the cornerstone of analytical geometry. We'll discuss the Cartesian system in depth, including solved examples, formulas, coordinates, and graph plotting.

Key Takeaways: geometry, coordinates, Cartesian plane, quadrants, geometry graph, Cartesian distance, Cartesian midpoint


Cartesian System

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The Cartesian system is the system that is used to label points in a plane and the number line gives rise to the Cartesian form. To comprehend the Cartesian coordinate system, we must have a thorough understanding of the number line. We have the following defined parameters in this system:

  • The X-axis and Y-axis are two perpendicular lines.
  • The plane is known as the Cartesian or coordinate plane, and the two lines X and Y, when combined, are known as the system's coordinate axes.
  • The plane is divided into four quadrants by two coordinate axes.
  • The Cartesian System's zero is the place where axes connect. The letter O will be used to represent this point. The origin's coordinates are written as (0, 0).
  • To specify the position of any point P in the plane, we must first measure the distance x along X and then the distance y parallel to Y to get from O to P. Negative distances are possible.

The video below explains this:

Coordinate Geometry Detailed Video Explanation:

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Cartesian Coordinates

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The x-coordinate of a point in the Cartesian system is its perpendicular distance from the y-axis. It is measured along the x-axis, which is positive in one direction and negative in the opposite. The x-coordinate is called abscissa.

The y-coordinate of a point in the Cartesian system is its perpendicular distance from the x-axis. The y-axis is used to calculate it. The ordinate refers to the y-coordinate.


Quadrants

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The quadrants divide the Cartesian plane into four equal pieces. These are numbered I, II, III, and IV in an anticlockwise sequence, beginning at the upper right and proceeding around in a clockwise orientation.

Points of Quadrants

I Quadrant: (+, +) It has a positive X coordinate and a positive Y coordinate.

II Quadrant: (-, +) It has a negative X coordinate and positive Y coordinate.

III Quadrant: (-, -) It has a negative X coordinate and negative Y coordinate.

IV Quadrant: (+, -) It has a positive X coordinate and a negative Y coordinate.

Quadrants
Quadrants

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Plotting the Graph

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Using the coordinate axes, it is simple to plot points on a given graph on the plane with an ordered number of pairs. If the coordinates (x,y) are given for a point P, then x is the abscissa and y is the ordinate.

The coordinate points will define the Cartesian plane's location. The horizontal axis is represented by the first point in the coordinates (x), and the vertical axis is represented by the second point in the coordinates (y).


Formulas

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The formulas of the Cartesian coordinate system make it easy to prove the numerous properties of lines, curves, and planes in two and three dimensions. The distance formula, slope formula, midpoint formula, section formula, equations of a line in two and three dimensions, equations of curves, and equations of a plane are all part of the Cartesian coordinate system. The following are a few of these formulas:

  • Coordinate Distance Formula- The following is the formula for calculating the distance between two points (x1,y1) and (x2,y2):
    D= √(x2-x1)2+ (y2-y1)2
  • MidPoint Formula- The following is the formula of the midpoint between the two points (x1,y1) and (x2,y2):
    (x,y) = (x1+x2/2 , y1+y2/2 )
  • Section Formula- The section formula is useful for determining the coordinates of a point on a line segment that splits the line segment connecting the points (x1,y1) and (x2,y2) in the ratio m:n :
    (x,y) = (mx2+nx1/m+n, my2+ny1/m+n)

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Important Topics for JEE Main 

As per JEE Main 2024 Session 1, important topics included in the chapter coordinate geometry are as follows:

  • Shortest Distance Between Lines
  • Tangent
  • Quadrants
  • Cartesian Coordinates
  • Coordinate Distance Formula

Some memory based important questions asked in JEE Main 2024 Session 1 include:

  1. The shortest distance between the lines is? (x-1)/2 = (y + 1)/4 = (z - 1)/3 and (2x - 1)/5 = (y-2)/3 = z/3
  2. If a line L = 4x + 5y = 20 trisects two other lines L₁ and L2 that pass through the origin, then find the tangent made by the line L.
  3. Let R be the interior region between the lines 3x - y + 1 = 0 and x + 2y - 5 = 0 containing the origin. The set of all values of a for which points (a2 a + 1) lie is?
  4. Distance of (2, 4) from the line 2x + y + 2 = 0 measured parallel to the line root3 x+y+2 = 0 is?


Things to Remember

  • The X-axis and Y-axis are two perpendicular lines.
  • The plane is known as the Cartesian or coordinate plane, and the two lines X and Y, when combined, are known as the system's coordinate axes.
  • The plane is divided into four quadrants by the two coordinate axes.
  • The Cartesian System's zero is the place where the axes connect. The letter O will be used to represent this point. The origin's coordinates are written as (0, 0).
  • To specify the position of any point P in the plane, we must first measure the distance x along X and then the distance y parallel to Y to get from O to P. Negative distances are possible.
  • I Quadrant: (+, +) It has a positive X coordinate and a positive Y coordinate.
  • II Quadrant: (-, +) It has a negative X coordinate and a positive Y coordinate.
  • III Quadrant: (-, -) It has a negative X coordinate and negative Y coordinate.
  • IV Quadrant: (+, -) It has a positive X coordinate and a negative Y coordinate.
  • Coordinate Distance Formula= D= √(x2-x1)2+ (y2-y1)2
  • MidPoint Formula= (x,y) = (x1+x2/2 , y1+y2/2 )
  • Section Formula= (x,y) = (mx2+nx1/m+n, my2+ny1/m+n)

Also Read:


Sample Questions

Ques: What are the names of the horizontal and vertical lines used to establish a point's position in the Cartesian plane? What are the names of the parts of the plane that these two lines form? Write the name of the intersection of these two lines. (3 marks)

Ans: (i) The x-axis and y-axis are the horizontal and vertical lines used to calculate the position of any point in the Cartesian plane.

(ii) Quadrants are the names for the parts of the plane produced by these two lines, the x-axis and the y-axis.

(iii) The origin is the location where these two lines intersect.

Ques: Write the coordinates of the given points- A, B, C, D and E. (3 marks)

Ans: The coordinates of the points are as follows-

  • A is (3, -2)
  • B is (3, 2)
  • C is (1, -1)
  • D is (3, -1)
  • E is (-2, -4)

Ques: Without plotting the points indicates the quadrant in which they will lie, if (3 marks)
(i) ordinate is 4 and abscissa is – 6
(ii) abscissa is – 3 and ordinate is – 2
(iii) abscissa is – 7 and ordinate is 5
(iv) ordinate is 8 and abscissa is 4

Ans: (i) the point is (-6, 4).

Hence, the point lies in the II quadrant.

(ii) The point is (-3,-2).

Hence, the point lies in the III quadrant.

(iii) The point is (-7, 5).

Hence, the point lies in the II quadrant.

(iv) The point is (8, 4).

Hence, the point lies in the I quadrant.

Ques: Find the distance, if given (-2,-6) and (3, 4). (3 marks)

Ans: Coordinate Distance Formula= D= √(x2-x1)2+ (y2-y1)2

We know, x1= -2, x2= 3, y1= -6 and y2= 4

So by putting the values in the formula, we get-

D= √(3-(-2))2+ (4-(-6))2

D= √52+ 102

D= √125 = 5√5

Ques: Find the midpoint of the given coordinates- (6,3) and (-6, -3). (3 marks)

Ans: Mid Point Formula= (x,y) = (x1+x2/2 , y1+y2/2 )

We know that, x1 = 6, x2= -6, y1= 3 and y2= -3.

By, putting the values in the formula we get-

(x, y)= (6 + (-6))/2, (3 + (-3) )/2

(x , y )= 0/2, 0/2

(x, y) = 0, 0.

Therefore, its midpoint will be the origin.

Ques: Find the distance, if given (5, 1) and (6, 3). (3 marks)

Ans: Coordinate Distance Formula= D= √(x2-x1)2+ (y2-y1)2

We know, x1= 5, x2= 6, y1= 1 and y2= 3

So by putting the values in the formula, we get-

D= √(6-5)2+ (3-1)2

D= √12+ 22

D= √5

Ques: Find the midpoint of the given coordinates- (4, 2) and (6, 8). (3 marks)

Ans: MidPoint Formula= (x,y) = (x1+x2/2 , y1+y2/2 )

We know that, x1 = 4, x2= 6, y1= 2 and y2= 8.

By, putting the values in the formula we get-

(x, y)= (4+6)/2, (2+8)/2

(x , y )= 10/2, 10/2

(x, y) = 5, 5

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CBSE X Related Questions

  • 1.
    If the zeroes of a polynomial p(x) are $-3$ and 8, then p(x) equals

      • $x^2 + 5x - 4$
      • $(x + 3) (-x + 8)$
      • $a(x^2 + 5x - 24)$
      • $x^2 - 24$

    • 2.
      Two water taps together can fill a tank in $8\frac{8}{9}$ hours. The tap of larger diameter takes 4 hours less than the smaller one to fill the tank separately. Find the time in which each tap can separately fill the tank.


        • 3.
          A bag contains 25 balls. Some of them are yellow and others are green. One ball is drawn at random. If probability of getting a green ball is $3/5$, then find the number of yellow balls.


            • 4.
              The dimensions of a window are $156\text{ cm} \times 216\text{ cm}$. Arjun wants to put grill on the window creating complete squares of maximum size. Determine the side length of the square and hence find the number of squares formed.


                • 5.
                  Prove that $14 - 2\sqrt{3}$ is an irrational number, given that $\sqrt{3}$ is irrational.


                    • 6.
                      An arc of length $2.2\text{ cm}$ subtends an angle $\theta$ at the centre of the circle with radius $2.8\text{ cm}$. The value of $\theta$ is

                        • $50^\circ$
                        • $60^\circ$
                        • $45^\circ$
                        • $30^\circ$

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