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NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 

 

NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 are created by Maths experts to help you revise the concepts of this exercise easily. The second exercise of Chapter 11 Mensuration is about finding the area of a trapezium, general quadrilateral, and polygon. There is no specific formula for finding the area of these figures. You need to divide the main shape into different simpler shapes and find the surface area. Our Maths experts have provided stepwise solutions to all 11 questions of this exercise. 

 

NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Exercise 11.2 are important for students as they help in:

  • Resolving doubts related to the exercise
  • Provide a reference for solving the NCERT exercise questions 
  • Include stepwise solutions for all the questions of this exercise 
  • Include comprehensive explanations
  • Are based on the latest CBSE exam pattern and syllabus for Class 8 Maths 

About NCERT Class 8 Maths Chapter 11 Mensuration Ex 11.2 

 

Surface Area of Different Shapes

Rectangle 

a x b, where a is the length of the rectangle and b is the breadth of the rectangle

Square

a x a, where a is the length of one side of the square

Triangle 

½ x b x h, where b is the length of the base and h is the height of the triangle

Circle 

πr2 , where r is the radius of the circle 

Parallelogram

b x h, where b is the breadth and h is the height of the parallelogram 


 

Surface Area of Different Solids

Cube 

6l2, where l is the length of one side of the cube 

Cuboid 

2(lb + bh + hl), where l is the length, b is the breadth and h is the height of the cuboid

Cylinder 

2πr(r + h), where r is the radius and h is the height of the cube 

Area of a Trapezium 

A trapezium is a quadrilateral whose two sides are parallel to each other. Area of trapezium can be found in two ways: 

  1. By splitting the figure 

In the figure given below, the area of trapezium ABECD can be found by calculating the area of rectangle ABCD and area of triangle DEC. 


 

  1. By using the formula 

Area of trapezium can be calculated using the formula:

 

Area of a general quadrilateral 


 

The area of a general quadrilateral can be given by:

Where h1 and h2 are the height of both the triangles and d is the length of the common diagonal. 

 

Area of Rhombus


 

Area of a rhombus is given by:

 

Area of a polygon 

 

There is no specific formula for finding the area of a polygon. It can be found only by splitting the figure. For example, the area of the octagon given below can be found by adding the areas of sections A, B and C. 

 

Download Free NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 

 

Exercise 11.2 includes 11 questions. Each of them is a word problem that you have to analyse and solve based on the given information. Let us see what kind of questions are included in this exercise:

 

Ex 11.2 Q1: In this question, you are given that the shape of the top surface of a table is a trapezium. You have to find its area if its parallel sides are 1 m and 1.2 m and the perpendicular distance between them is 0.8 m.

 

Ex 11.2 Q2: In this question, you are given the area of a trapezium and the length of one of its parallel sides along with its height. You have to find the length of the other parallel side of the trapezium. 

 

Ex 11.2 Q3: In this question, you are given that the length of the fence of a trapezium-shaped field ABCD is 120 m. Also, Side AB is perpendicular to the parallel sides AD and BC. If BC = 48 m, CD = 17 m and AD = 40 m, you have to find the area of this field. 

 

Ex 11.2 Q4: In this question, you are given that the diagonal of a quadrilateral shaped field is 24 m and the perpendiculars dropped on it from the remaining opposite vertices are 8 m and 13 m. You have to find the area of the field.

 

Ex 11.2 Q5: In this question, you are given that the diagonals of a rhombus are 7.5 cm and 12 cm. You have to find its area.

 

Ex 11.2 Q6: In this question, you have to find the area of a rhombus whose side is 5 cm and whose altitude is 4.8 cm. If one of its diagonals is 8 cm long, you need to find the length of the other diagonal.

 

Ex 11.2 Q7: This question states that the floor of a building consists of 3000 rhombus-shaped tiles and each of its diagonals is 45 cm and 30 cm in length. You have to find the total cost of polishing the floor if the cost per m2  is rupees 4.

 

Ex 11.2 Q8: In this question, you are given that Mohan wants to buy a trapezium-shaped field. Its side along the river is parallel to and twice the side along the road. If the area of this field is 10500 m2 and the perpendicular distance between the two parallel sides is 100 m, find the length of the side along the river.

 

Ex 11.2 Q9: In this question, you are given that the top surface of a raised platform is in the shape of a regular octagon. You have to find the area of the octagonal surface.

 

Ex 11.2 Q10: In this question, you are given a figure of a pentagonal shaped park. For finding its area, Jyoti and Kavita divided it into two different ways. You have to find the area of this park using both ways. Also, you have to suggest some other way of finding its area, if possible. 

 

Ex 11.2 Q11: In this question, you have given a diagram of a picture frame with outer dimensions = 24 cm × 28 cm and inner dimensions 16 cm × 20 cm. You have to find the area of each section of the frame if the width of each section is the same.

 

Learn how to solve all the 11 questions of this exercise with the help of our NCERT Solutions for Class 8 Maths Chapter 11 Exercise 11.2. All the solutions are based on the latest CBSE Class 8 Maths syllabus. Download them for free and start practising. 

NCERT Class 8 Maths Chapter 11 Mensuration Ex 11.2 FAQs

 

  1. What are the main topics covered in Exercise 11.2 of NCERT Class 8 Maths Chapter 11 Mensuration?

 

The second exercise of NCERT Class 8 Maths Chapter 11 Mensuration is based on finding the area of a trapezium, general quadrilateral, and polygon. 

 

  1. How can I get good marks in NCERT Class 8 Maths Chapter 11 Mensuration? 

 

At askIITians you can find many study resources and learning materials for Class 8 Maths Chapter 11 Mensuration. These include revision notes, mind maps, flashcards, previous year questions, worksheets, NCERT Solutions and more. 

 

  1. How to solve NCERT Class 8 Maths Chapter 11 Mensuration exercise 11.2?

 

You must read the questions carefully and draw a rough diagram with the help of the information given to you. Make sure you remember how to find the area of different shapes like square, rectangle, circle, triangle, trapezium, parallelogram, rhombus, etc. 

 


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