**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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