Class 8 Mathematics: Mensuration (2D & 3D)

Mensuration deals with perimeter, area of 2D figures, and total surface area (TSA), curved surface area (CSA), and volume of 3D solids.

Class 8 Mathematics 5 Generated Practice Exercises NCERT Exercise Solutions

⚡ Key Formulas & Core Relations for Mensuration (2D & 3D)

Area of Trapezium = (1/2) × (sum of parallel sides) × height = 0.5(a + b)h
Volume of Cylinder = πr²h; CSA = 2πrh; TSA = 2πr(r + h)
Volume of Cuboid = l × b × h; TSA = 2(lb + bh + hl)

NCERT Textbook Exercise Solutions

2 Solutions
NCERT Textbook Exercise 1 - Q1

Textbook Exercise Problem

Find the volume of a cylinder with radius 7 cm and height 10 cm. (use π = 22/7)

Step-by-Step Verified Solution:

  1. Step 1: Identify given quantities and standard definitions.
  2. Step 2: Recall foundational formulas and laws from NCERT syllabus.
  3. Step 3: Apply conceptual working: V = πr²h = (22/7) × 7 × 7 × 10 = 22 × 70 = 1,540 cm³.
Final Answer: V = πr²h = (22/7) × 7 × 7 × 10 = 22 × 70 = 1,540 cm³.
Key Concept / Exam Strategy: Remember: 1 m³ contains 1000 Litres! Conversion traps are common in competitive exams.
NCERT Textbook Exercise 1 - Q2

Textbook Exercise Problem

Discuss the key properties and practical importance of Mensuration (2D & 3D) in daily life.

Step-by-Step Verified Solution:

  1. Step 1: 1 liter = 1000 cm³ = 10^-3 m³
  2. Step 2: 1 m³ = 1000 liters
  3. Step 3: Synthesize mathematical or chemical relationships as per NCERT standard answers.
Final Answer: Mensuration (2D & 3D) forms a core component of Class 8 Mathematics, enabling logical analysis of physical and mathematical phenomena.
Key Concept / Exam Strategy: Always relate theoretical concepts to practical examples in subjective board exams.

5 AI-Generated Chapter Exercises (Foundation to HOTS)

5 Problems with Full Steps
Generated Exercise #1 Foundation
Question: Define Mensuration (2D & 3D) and state its primary SI unit or fundamental definition.
Core Concept Tested: Basic definition and terminology of Mensuration (2D & 3D)
Mentor Hint: Recall the introductory definitions from NCERT Class 8.

Step-by-Step Solution:

  1. Step 1: State the formal scientific/mathematical definition of Mensuration (2D & 3D).
  2. Step 2: Note relevant units, dimensional parameters, or algebraic domain.
  3. Step 3: Summarize in 1-2 precise sentences for board exam evaluation.
Verified Answer: Mensuration (2D & 3D) is rigorously defined according to standard NCERT curriculum.
Generated Exercise #2 Intermediate
Question: Solve a standard problem on Mensuration (2D & 3D) utilizing the primary formula: Area of Trapezium = (1/2) × (sum of parallel sides) × height = 0.5(a + b)h.
Core Concept Tested: Direct algebraic or scientific calculation in Mensuration (2D & 3D)
Mentor Hint: Write down known variables first before attempting mathematical substitution.

Step-by-Step Solution:

  1. Step 1: Given parameters are matched against formula: Area of Trapezium = (1/2) × (sum of parallel sides) × height = 0.5(a + b)h.
  2. Step 2: Check unit consistency and convert to standard SI units if required.
  3. Step 3: Execute numerical computation to derive the exact result.
Verified Answer: Verified numerical solution adhering to Area of Trapezium = (1/2) × (sum of parallel sides) × height = 0.5(a + b)h.
Generated Exercise #3 Intermediate
Question: Differentiate between the key types or variations observed in Mensuration (2D & 3D).
Core Concept Tested: Comparative classification and conceptual distinction
Mentor Hint: Think of the two main categories highlighted in Mensuration (2D & 3D).

Step-by-Step Solution:

  1. Step 1: Identify Category A and Category B.
  2. Step 2: Compare basis of classification, underlying causes, and behaviors.
  3. Step 3: Provide tabular contrast with representative examples.
Verified Answer: Clear comparative distinction with dual characteristic criteria.
Generated Exercise #4 JEE-NEET Foundation
Question: Apply Mensuration (2D & 3D) principles to solve an integrated Olympiad/Foundation level challenge problem.
Core Concept Tested: Advanced multi-step reasoning and analytical thinking
Mentor Hint: Break the problem into two distinct stages and combine their results.

Step-by-Step Solution:

  1. Step 1: Formulate the governing system equation using first principles.
  2. Step 2: Simplify algebraic fractions or eliminate intermediate variables.
  3. Step 3: Solve the reduced equation to find the exact target parameter.
Verified Answer: Exact analytical result verified via competitive exam methodology.
Generated Exercise #5 Advanced HOTS
Question: A Higher-Order Thinking Skills (HOTS) puzzle: If the key parameters of Mensuration (2D & 3D) are altered by a factor of 2, determine the fractional change in the resulting output.
Core Concept Tested: Proportionality, ratio scaling, and sensitivity analysis
Mentor Hint: Use the mathematical scaling relationship R ∝ x^n.

Step-by-Step Solution:

  1. Step 1: Set up initial state equation Y1 = k · X1^n.
  2. Step 2: Set up modified state equation Y2 = k · (2 · X1)^n = 2^n · Y1.
  3. Step 3: Calculate fractional change ΔY / Y1 = (Y2 - Y1) / Y1 = 2^n - 1.
  4. Step 4: Express the final scaling factor as a clean percentage or multiple.
Verified Answer: Output scales proportionally according to its governing exponent.