Notes on Co-ordinate Geometry | Grade 7 > Optional Maths > Co-ordinate Geometry | KULLABS.COM

• Note
• Things to remember
• Videos
• Exercise
• Quiz

Introduction:

Rene Descartes is a famous mathematician who has invented the concept of coordinate geometry in 17thcentury . Algebra and Geometry is an overlapping portion which we now say Co-ordinate Geometry . Co-ordinate Geometry is a branch of mathematics which deals with the combination of algebra and geometry .Note;it deals with the exact location of a point ,line and surface.

Things to know; we need to know how we locate a point on a number line which will be comfortable with a plane . the line below is a number line .Here we are standing at 0 and right side of 0 is a positive and left side of 0 is negative .

Describing the cartesian coordinate plane .

Here, a cartesian coordinate plane is also known as a rectangular coordinate system . Which is made up of two number lines and it forms axes .

1. The horizontal number line is the X-axis .It is also called abscissa .
2. The vertical number lines are the Y- axis . It is also known as ordinate .
3. The two line intersecting part is called Origin . At this point, both number lines are zero .

Axes divided into four quadrants which marked on the graph with roman numerals.

Each point on the graph is associated with an ordered pair . On the plain figure, the point can be described by its X and Y coordinates .Here coordinates are written as the pair : ( X , Y ). When dealing with an ( x , y ), x and y coordinates are always first and second respectively . There are two values in the ordered pair, so we should be careful that it associates to only one point on the graph .In the graph , we have point A and to know the point A let's look at the origin . So, to reach Awe move four (4) steps to the right and stop . Again we need to move two ( 2 ) step up to get the exact point A . Hence, the coordinate of point A in ( 4 , 2 )As its took us 4 steps on the right and 2 steps above to reach the point .Here x-axis has elongated both ways .So, we can represent it by XX'; where X represents positive and X' represents negative side . Same ways Y axis is elongated up and down both forming YY' where Y represents positive and Y' representing negative side .

As we know, from theory and examples that four quadrants with the help of two axis quadrant I, quadrant II, quadrant III, quadrant IV, respectively .Even can generalises the nature of X' s and Y' s and studies their nature as below.

 Quadrant X-coordinate y-coordinate Nature I positive positive ( a, b ) II positive positive (-a,b ) III positive positive (-a,-b) IV positive positive (a,- b )

Similarly,

All the points on the x-axis will be of nature ( a, 0 ) if it is on the right side of the origin and (-a, 0 ) if it is on the left side of the origin . On the other hand, all the points on the y-axis will be of nature ( 0, b ) if it is above origin and ( 0, -b ) if is below the origin .

Distance Between Two Points:

The distance between two points can be determined by how much we have moved it. If the points are being at the axes it becomes easy for us but if we are moving arbitrarily we need to think. The following example illustrates it: (Figure)

• A rectangular coordinate is made up of two number lines.
• The horizontal number line is x- axis  and vertical number line is y- axis.
• x-axis  and y-axis  also known as abcissa and ordinate respectively.
.

### Very Short Questions

Solution

X(-3, 2), Y(-1, 2) and Y(4,2) represents a triangle. When measured with a scale two sides XY and YZ are equal so it presents an isosceles triangle.

Solution

According to the question,

O(0,0), Q(4,0) and R(0,5)  is  representing a triangle as it has 3 sides and it is a  right angled triangle as ∠ROQ is 90º as measured with protector.

Solution:

A(1,-1), B(7,3), C(4,6) & D(-2, 2) represents a quadrilateral as it has four sides. Since, the opposite sides are equal it represents a rectangle.

Solution:

Since point P corresponds to 2 on the x-axis and -3 on the y-axis, then P 's ordered pair is coordinate is (2, -3).

Solution

P(1,2) and Q(3, 2)

Here, let P(1, 2) be (x1, y1) and Q(3, 2) be (x2, y2)

Now, x- component = x2 - x1

= 3 - 1

= 1

y- component = y2 - y1

= 2 - 2

= 0

Here, PQ = 1 units (As it has travelled is only one axis )

0%

10 units
5units
6 units
7units
• ### ______________________ is the founder of coordinate geometry.

Newton
Robbins
Rene Descrates

origin
cartesian
ordinate
abcissa

abcissa
Ordinate
axis
origin

5 units
7 units
9 units
11 units
• ### Find the distance between M(2, 1) and N(5, 3)

(sqrt{8}) units
(sqrt{15}) units
(sqrt{11}) units
(sqrt{13}) units

7 units
11 units
12 units
9 units

6 units
5 units
8 units
7 units

6 units
5 units
8  units
7 units

3, 2
2, 5
5, 1
3, 4

## ASK ANY QUESTION ON Co-ordinate Geometry

No discussion on this note yet. Be first to comment on this note