NCERT Class 9 Maths Lab Manual – Find a Hidden Picture by Plotting
OBJECTIVE
To find a hidden picture by plotting and joining the various points with given coordinates in a plane.
Materials Required
- Cardboard
- White paper
- Graph paper
- Scissors
- Adhesive
- Geometry box
Prerequisite Knowledge
Knowledge of cartesian coordinate system.
Theory
For knowledge of cartesian coordinate system refer to Activity 16.
Procedure
- Take a cardboard of suitable size and paste a white paper on it.
- Take a graph paper and paste it on the white paper.
- Draw two coordinate axes X’OX and Y’OY. (see Fig. 17.1)
- Plot the points A, B, C,… with given coordinates (a, b), (c, d), (e, f), …. respectively, (see Fig. 17.2)
- Join the points in the given order say A → B → C → D → … → A. (see Fig. 17.3)
Demonstration
By joining the points as per given instructions, a hidden picture of an ‘aeroplane’ is formed.
Observation
From Fig. 17.3
Coordinates points A, B,C,D, …….. ,
are …….. , …….. , …….. , …….. , …….. , …….. , …….. , and hidden picture is of …….. .
Result
We have found the hidden picture by plotting and joining the various points with givèn coordinates in a plane.
Application
This activity is helpful in understanding the plotting of points in a cartesian plane which is further useful in preparing the road maps and sitting plan of the classroom.
Viva Voce
Question 1:
Are the ordinates of all the points on Y-axis zero?
Answer:
No, because their distance from X-axis is not zero.
Question 2:
Are the abscissae of all the points on the Y-axis zero?
Answer:
Yes, because their distance from Y-axis is zero as they lie on Y-axis.
Question 3:
What is the coordinates of a point at origin?
Answer:
(0,0)
Question 4:
x-coordinate and y-coordinate taken together are called …………..?
Answer:
cartesian coordinates
Question 5:
What is the maximum number of abscissa points on the X-axis?
Answer:
Infinite
Question 6:
What would be the value of (abscissa A – abscissa B), if two points are A(3, 4) and B (-2, 5)?
Answer:
3-(-2) = 3+ 2 = 5
Question 7:
What is the perpendicular distance of the point (6, 4) from the X-axis?
Answer:
4 units
Question 8:
Are there any points which do not lie in any of the quadrants? If yes, then where do they lie?
Answer:
Yes, they He on axes.
Question 9:
If any line is perpendicular to the X-axis, then which axis is parallel to it?
Answer:
If any line is perpendicular to the X-axis, then it is parallel to Y-axis.
Question 10:
Is it correct to say that horizontal axis is Y-axis and vertical axis is X-axis?
Answer:
No, because in standard coordinate system horizontal line is always X-axis and vertical line is always Y-axis.
Suggested Activity
Trace the corner points of a picture on graph paper and get some points. After joining them get the same picture.
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