thi Wisewoods E.M. High School
Draw rectangle with length and breadth 9 cm and 5 cm respectively.
Now draw second rectangle with same area but the length of
rectangle is 15 cm. Now study the rectangles and write your
observation.
Now next time take new length 45 cm and find what should be the breadth
if area of rectangle remains same.
Write
(a) A monomial which when divided by 3x² gives 9xy.
(b) A binomial which when divided by 3x² gives 9xv.



Answer :

Alright, let's go through each part step-by-step.

### Part 1: Drawing the Rectangles
1. First Rectangle:
- Length = 9 cm
- Breadth = 5 cm
- Area Calculation:
[tex]\[ \text{Area}_1 = \text{Length}_1 \times \text{Breadth}_1 = 9 \, \text{cm} \times 5 \, \text{cm} = 45 \, \text{cm}^2 \][/tex]

2. Second Rectangle:
- Given Area (same as the first rectangle): [tex]\( \text{Area}_1 = 45 \, \text{cm}^2 \)[/tex]
- New Length = 15 cm
- Finding the New Breadth:
For the area to remain the same, we use the same area formula:
[tex]\[ \text{Area}_2 = \text{New Length} \times \text{Breadth}_2 \][/tex]
Since [tex]\(\text{Area}_2 = 45 \, \text{cm}^2 \)[/tex] and [tex]\(\text{New Length} = 15 \, \text{cm} \)[/tex]:
[tex]\[ 45 \, \text{cm}^2 = 15 \, \text{cm} \times \text{Breadth}_2 \][/tex]
[tex]\[ \text{Breadth}_2 = \frac{45 \, \text{cm}^2}{15 \, \text{cm}} = 3 \, \text{cm} \][/tex]

3. Third Rectangle:
- Given Area (same as the first rectangle): [tex]\( \text{Area}_1 = 45 \, \text{cm}^2 \)[/tex]
- New Length = 45 cm
- Finding the New Breadth:
Similarly, using the area formula:
[tex]\[ 45 \, \text{cm}^2 = 45 \, \text{cm} \times \text{Breadth}_3 \][/tex]
[tex]\[ \text{Breadth}_3 = \frac{45 \, \text{cm}^2}{45 \, \text{cm}} = 1 \, \text{cm} \][/tex]

### Observations
- First Rectangle: 9 cm (length) and 5 cm (breadth)
- Second Rectangle: 15 cm (length) and 3 cm (breadth)
- Third Rectangle: 45 cm (length) and 1 cm (breadth)

Observation: The area of the rectangles remains constant at [tex]\(45 \, \text{cm}^2\)[/tex]. However, as the length increases, the breadth decreases proportionally to ensure that the product of length and breadth (i.e., the area) remains the same.

### Part 2: Algebraic Expressions

(a) Finding the monomial:
- Given: The monomial divided by [tex]\(3x^2\)[/tex] gives [tex]\(9xy\)[/tex].
- Let the monomial be [tex]\(m\)[/tex].
- Form the equation:
[tex]\[ \frac{m}{3x^2} = 9xy \][/tex]
[tex]\[ m = 9xy \times 3x^2 \][/tex]
[tex]\[ m = 27x^3y \][/tex]
- So, the monomial is [tex]\(27x^3y\)[/tex].

(b) Finding the binomial:
- Given: The binomial divided by [tex]\(3x^2\)[/tex] gives [tex]\(9xv\)[/tex].
- Let the binomial be [tex]\(b\)[/tex].
- Form the equation:
[tex]\[ \frac{b}{3x^2} = 9xv \][/tex]
[tex]\[ b = 9xv \times 3x^2 \][/tex]
[tex]\[ b = 27x^3v \][/tex]
- So, the binomial is [tex]\(27x^3v\)[/tex].

### Summary
- Areas:
- First Rectangle: [tex]\(45 \, \text{cm}^2\)[/tex]
- Second Rectangle: Length = 15 cm, Breadth = 3 cm
- Third Rectangle: Length = 45 cm, Breadth = 1 cm
- Algebraic Expressions:
- Monomial: [tex]\(27x^3y\)[/tex]
- Binomial: [tex]\(27x^3v\)[/tex]

This systematic process ensures that the area calculations and algebraic derivations are clear and accurate.