NCERT Solutions For Class 7 Maths Chapter 11

NCERT Solutions Class 7 Maths Perimeter and Area

Ncert Solutions For Class 7 Maths Chapter 11 PDF Download

The NCERT solutions for class 7 maths chapter 11 contains the different portions of mathematics. Class 7 maths chapter 11 deals with the chapter of Perimeter and Area. The NCERT solutions for Class 7 contains the different chapters with the various solutions to the problems. Some of the major chapters that are introduced in the subject of mathematics. With the help of NCERT Solutions for Class 7 Maths, one can easily solve for different problems for the different topics in the subject of mathematics. The major topics dealing with Perimeter and Area deals with the major units being found by the various calculations. The area, perimeter and the price are some of the major metrics that need to be found in the subject of mathematics. Finding other metrics such as breadth and area along with the perimeter are some of the different metrics that can be found. Solving various problem sets along with a host of different examples is important to understand the major types of problems along with figuring out the different metrics such as Perimeter and Area.

NCERT Solutions For Class 7 Maths Chapter 11 Exercises

Exercise 11.1

 

Q1. Find

                (a) the area of the land

                (b) the price of the land,

                If the land is of rectangular shape measuring 300 m in length and 400 m in breadth.  The cost of 1m2 land is Rs. 10000.

Ans:       (a) Area = Length (l) x Breadth (b)

= 300 x 400

= 120000 m2

(b) Cost of 1 m2 land = Rs 10000

Cost of 120000 m2 land = 10000 x 120000 = Rs 1200000000.

 

Q2. The perimeter of a park is 240m. Determine the area.

Ans:       Perimeter = 240 m

4 x Length of a side of the park = 240

Length of a side of park = 240/4 = 60 m

Area = (Length of a side of park) 2 = (60)2 = 3600 m2

 

Q3. The area and length of a rectangular plot of land are 1200 m2 and 40 m respectively. Determine its perimeter.  

Ans:       Area = Length (l) x Breadth (b) = 1200 m2

= 40 x Breadth = 1200

= Breadth = 1200/40 = 30

Perimeter = 2 (Length (l) + Breadth (b) )

= 2 (30 + 40) = 2 (70) = 140 m

 

Q4. Find the breadth and area if the perimeter and length of the rectangular sheet is 120 cm and 40 cm respectively.

Ans:       Perimeter = 2 (Length + Breadth) = 120 cm

2 (40 + Breadth) = 120

40 + b = 60

b = 6O – 40 =20 cm

Area = Length (l) x Breadth (b) = 40 x 20 = 800 cm2

 

Q5. The area of the rectangular park is equal to a square park. If the length of rectangular park measures 80m and the side of the square park is 100 m .Determine the breadth of the rectangular park.

Ans:       Area of the square park = (side of the park)2 = (100)2 = 10000 m2

Area of the rectangular park = Length (l) x Breadth (b) = 10000

80 x Breadth = 10000

Breadth = 125 m

 

Q6. The length and breadth of a wire whose shape is a rectangle are 22 and 40 respectively. The wire is then reshaped into a square. Determine the side of the square and find out which shape encloses more area.

Ans:       Perimeter of the rectangle = Perimeter of the square

2 (Length (l) + Breadth (b)) = 4 x Side

2 (22 + 40) = 4 x Side

2 x 62 = 4 x Side

Side =124/4 = 31 cm

Area of the rectangle = 22 x 40 = 880 cm2

Area of the square = (Side)2 = 31 x 31 = 961 cm2

Therefore, the square shaped wire encloses more area.

 

Q7. If the breadth and perimeter of a rectangle are 40 cm and 120 cm respectively, determine the length and area of the rectangle.

Ans:       Perimeter = 2 (Length (l) + Breadth (b)) = 120

2 (Length + 40) = 120

Length + 40 = 60

Length = 60 – 40 = 20 cm

Area = Length (l) x Breadth (b) = 20 x 40 = 800 cm2

 

Q8. A door is fitted in a wall whose length measures 1 m and breadth measures 2 m. The length and breadth of the wall are 5 m and 3.5 m (in the given figure). The price of white washing the wall is Rs 10 per m2. Find the cost of whitewashing the wall without the door.

8

Ans:       Area of the wall = 5 x 3.5 = 17.5 m2

Area of the door = 2x 1 = 2 m2

Area to be white-washed = 17.5 – 2 = 15.5 m2

Cost of white-washing 1 m2 area = Rs 10

Cost of white-washing 15.5 m2 area = 15.5 x 10 = Rs 155

 

Exercise 11.2

 

Q1. Determine the area of the parallelograms in the diagram given below

Ans:

9

(a) Area of a parallelogram = Height x Base

Base = 8 cm

Height = 5 cm

Area = 8 x 5 = 40 cm2

(b) Area of a parallelogram = Height x Base

Base = 6 cm

Height = 4 cm

Area = 6 x 4 = 24 cm2

(c) Area of a parallelogram = Height x Base

Base = 4.5 cm

Height = 7 cm

Area = 4.5 x 7 = 31.5 cm2

(d) Area of a parallelogram = Height x Base

Base = 9.6 cm

Height = 10 cm

Area = 9.6 x 10 = 96 cm2

(e) Area of a parallelogram = Height x Base

Base = 8.8 cm

Height = 4 cm

Area = 8.8 x 4 = 35.2 cm2

 

Q2. Determine the area of the triangles .

Ans:

10

(a) Area of a triangle \(= \frac{1}{2}\times Base \times height\)

Height = 6 cm

Base = 8 cm

Area \(= \frac{1}{2}\times 8 \times 6\) = 48 cm2

(b) Area of a triangle \(= \frac{1}{2}\times Base \times height\)

Height = 6.4 cm

Base = 10 cm

Area \(= \frac{1}{2}\times 10 \times 6.4\) = 64 cm2

(c) Area of a triangle \(= \frac{1}{2}\times Base \times height\)

Height = 6 cm

Base = 8 cm

Area \(= \frac{1}{2}\times 8 \times 6\) = 48 cm2

(d) Area of a triangle \(= \frac{1}{2}\times Base \times height\)

Height = 4 cm

Base = 6 cm

Area \(= \frac{1}{2}\times 4 \times 6\) = 24 cm2

 

Q3. Fill the empty cells:

S. No Base Height Area of parallelogram
A 10 cm 124 cm2
B 12 cm 96 cm2
C 7 cm 91 cm2
D 11 cm 121 cm2

Ans:

(a) Area of a parallelogram = Height x Base

B = 10 cm

H =?

Area = 124 cm2

10 x h = 124

\(h = \frac{124}{10}=12.4\)

So, the height of the parallelogram is 12.4 cm

(b) Area of a parallelogram = Height x Base

B =?

H = 12 cm

Area = 96 cm2

b x 12 = 96

\(b = \frac{96}{12}=8\)

So, the base of the parallelogram is 8 cm

(c) Area of a parallelogram = Height x Base

B = 7 cm

H =?

Area = 91 cm2

7 x h = 91

\(h = \frac{91}{7}=13\)

So, the height of the parallelogram is 13 cm

(d) Area of a parallelogram = Height x Base

B = 11 cm

H =?

Area = 121 cm2

11 x h = 121

\(h = \frac{121}{11}=11\)

So, the height of the parallelogram is 11 cm

 

Q4. Fill in the blanks:    

Base Height Area of triangle
12 24 cm2
30 60 cm2
22 66 cm2

Ans:      

(a) Area of a triangle \(= \frac{1}{2}\times Base \times height\)

Height = ?

Base = 12 cm

Area \(= \frac{1}{2}\times Base \times height\) = 24 cm2

\(\frac{1}{2}\times 12 \times h = 24\)

\(h = \frac{24\times 2}{12} = 4 cm\)

Therefore, the height of the triangle is 4 cm

(b) Area of a triangle \(= \frac{1}{2}\times Base \times height\)

Height = 30 cm

Base = ?

Area \(= \frac{1}{2}\times Base \times height\) = 60 cm2

\(\frac{1}{2}\times b \times 30 = 60\)

\(h = \frac{60\times 2}{30} = 4 cm\)

Therefore, the base of the triangle is 4 cm

(c) Area of a triangle \(= \frac{1}{2}\times Base \times height\)

Height =?

Base = 22 cm

Area \(= \frac{1}{2}\times Base \times height\) = 66 cm2

\(\frac{1}{2}\times 22 \times h = 24\)

\(h = \frac{66\times 2}{22} = 6 cm\)

Therefore, the height of the triangle is 6 cm.

 

Q5. ABCD is a parallelogram (in the given figure). BX is the height from B to CD and BY is the height from B to AD. If CD = 12 cm and BX = 7.6 cm.

Find:      (a) the area of the parallelogram ABCD

                (b) BY, if AD = 8 cm.

Ans:

11

(a) Area of parallelogram = Base x Height = CD x BX

= 7.6 x 12 = 91.2 cm2

(b) Area of parallelogram = Base x Height = AD x BY = 91.2 cm2

BY x 8 = 91.2

BY = 91.2/8 =11.4 cm

 

Q6. SL and QM are the heights on sides PQ and PS respectively of parallelogram PQRS (in the given figure). If area of parallelogram is 1470 cm2, AB = 35 cm and AD = 49 cm, find the length of BM and DL.

`Ans:

12

Area of a parallelogram = Height x Base = PQ x SL

1470 = 35 x SL

DL = \(\frac{1470}{35}\) = 42 cm

Also, PS x QM = 1470

1470 = 49 x QM

\(QM = \frac{1470}{35} = 30\ cm\)

 

 Q7. ABC is right angled at A (in the given figure). AD Is perpendicular to BC. If AB = 5 cm, BC = 13 cm and AC = 12 cm, determine the area of triangle ABC. Also find the length of AD.

Ans:

13

Area of a triangle \(= \frac{1}{2}\times Base \times height\)  \(= \frac{1}{2}\times 5 \times 12\) = 30 cm2

Also, area of triangle \(= \frac{1}{2}\times AD \times BC\)

\( 30 = \frac{1}{2}\times AD \times 13\)

\(\frac{30\times 2}{13}= AD\)

AD = 4.6 cm

 

Q8. Triangle ABC is isosceles with AB = AC = 7.5 cm and BC = 9 cm (in the given figure). The height AD from A to BC is 6 cm. Find the area of triangle ABC. What will be the height from C to AB i.e., CE?

Ans:

14

Area of triangle ABC \(= \frac{1}{2}\times Base \times height\) \(= \frac{1}{2}\times BC \times AD\)

\(= \frac{1}{2}\times 9 \times 6 = 27 cm2 \)

Area of triangle ABC \(= \frac{1}{2}\times Base \times height\) \(= \frac{1}{2}\times AB \times CE\)

\(27= \frac{1}{2}\times 7.5 \times CE\)

CE = 7.2

Thus, the above contains the solutions for the various problems. Some of the NCERT solutions for class 7 maths chapter 11 are unique and need to be solved. With the help of NCERT solutions class 7 it is easy enough for one to solve for various different problems for the students preparing for their exams. This topic is useful and helpful in calculating the breadth and height of different shapes. It primarily deals with figures such as rectangles, squares and circles. One can easily find the different metrics of parallelograms such as areas, length and height. Thus, these are the different NCERT solutions for class 7 maths, dealing with chapter 11. These are important solutions that need to be remembered for clearing the final exams. Class 7 deals with the various chapters of mathematics such as Integers, Rational Numbers, Perimeter and Area. Thus, these are some of the different solutions for class 7.