Cut and General cuboid rule

Duration: 8 min

This video lesson is available to enrolled students.

Return to /learn/UPPSC-COMPUTER-OPERATOR-GRADE-B/reasoning/mensuration-and-geometry/3d-mensuration-solid-figures/asset-cut-and-general-cuboid-rule after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. English Comprehension: Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Reading Comprehension, Vocabulary, Idioms and Phrases, Narrative Sequencing, Critical Reasoning
  2. Reasoning and Aptitude: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Analogy, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Logical Sequence Of Words, Seating Arrangements, Puzzle Solving (Puzzles), Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Data Sufficiency, Selection Decision Table (Decision Making), Calendar, Clock, Cubes & Dices, Data Arrangement, Venn Diagram, Analytical Reasoning (Counting Figures Reasoning), Number System, HCF LCM, Percentage, Ratio and Proportion (Ratios), Average, Profit and Loss, Simple Interest and Compound Interest, Speed Time and Distance, Mensuration and Geometry, Arithmetic, Mixture and Alligation, Age Problems, Data Interpretation, Alphabet and Word Tests, Numerical Reasoning, Number System, Averages, Mixtures and Alligation, Percentages, Series Completion, Analogy and Classification, Patterns in Two-Dimensional Figures, Coding and Decoding, Mathematical Operations, Direction Sense, Logical Deduction and Induction, Simplification and Approximation, Assembling and Grouping of Shapes, Transformation of Shapes, Three-Dimensional Patterns and Visualization, Cubes and Dice, Algebra, Traverse Surveying, Clocks and Calendars, Order, Ranking and Sequence, Constraint Puzzles, Syllogisms and Venn Diagrams, Ratio and Proportion, Mensuration, Permutations and Combinations, Project Monitoring, Resources and Safety, Profit, Loss and Discount, Sequences and Series, Powers, Surds and Logarithms, Subject-Verb Agreement, Sentence Completion, Geometry, Probability, Trigonometry, Measurement and Quantity Take-Off, Statistics, Data Sufficiency, Blood Relations, Speed, Time and Distance, Time and Work, Data Interpretation, Sequence and Series (Series), Algebra, Permutation and Combination, Combinatorics
  3. General Awareness: Physics, Chemistry, Biology, Geography, History, Polity, Indian Economy
  4. Computer Fundamentals: Basics of COA, Number System, Number Representation, Semiconductor Memories and Programmable Logic, Timing, Hazards and Testing, Processor Organization and Instructions, Number Systems and Codes, Combinational Logic Design, Combinational Logic Circuits, Number Systems and Codes
  5. Operating System: Introduction to OS, Unix OS, Linux OS
  6. C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  7. OOPS with C++ & Java: OOPS with C++, Java
  8. Database Management System: Basics of DBMS, SQL
  9. MS Office: MS Office Applications
  10. Internet & Web Technologies: Website, Browser & Services, Internet Fundamentals, Web Design & Development, Protocols & Services
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This lecture covers two main geometry topics: the cut and general cuboid rule, and calculating the longest diagonal of a cuboid. The first section explains that cutting a cube or cuboid into smaller pieces increases the number of pieces and surface area but does not change the total volume. Formulas are provided for calculating the side length of small cubes (a/n), the number of pieces (n^3 or pqr for a cuboid), and the cuts required without stacking (3(n-1) for a cube or (p-1)+(q-1)+(r-1) for a cuboid). The instructor uses visual grids and handwritten annotations to illustrate these concepts. The second section transitions to finding the longest diagonal of a cuboid using the formula d = √(a² + b² + h²). A worked example with dimensions 1.2 cm × 1.3 cm × 1.5 cm is solved, yielding an answer of approximately 2.23 cm from the given options (2.22, 2.32, 2.23, 2.35 cm). The final section briefly introduces a problem on cube surface area to diagonal, where a surface area of 13.5 m² is used with the formula S = 6a² to find a² = 2.25 and a = 1.5 m.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the concept that cutting a cube or cuboid into smaller pieces increases the number of pieces and surface area but does not change total volume. On-screen text displays key formulas: 'Side of each small cube = a/n', 'Number of small cubes = n^3', and 'Cuts required without stacking = 3(n - 1)'. The instructor draws a red grid on the screen to visually represent dividing a cube's faces, writing '1' inside one square. The general cuboid rule is introduced with text showing 'Number of pieces = pqr' and 'Cuts required without rearranging or stacking = (p - 1) + (q - 1) + (r - 1)'. The instructor circles 'a/n' and writes 'a/3' below it, suggesting a specific example where n=3.

  2. 2:00 – 5:00 02:00-05:00

    The lecture continues with the general cuboid rule, emphasizing that cutting does not change total volume. The instructor highlights formulas for side length, number of small cubes, and cuts required, drawing red circles around key terms like 'n', 'n^3', and 'a^3'. The slide then transitions to a new topic: finding the longest diagonal of a cuboid. A problem is presented with dimensions '1.2 cm × 1.3 cm × 1.5 cm' and four options listed (2.22, 2.32, 2.23, 2.35 cm). A wireframe cuboid with a red diagonal arrow is shown at the bottom left. The instructor writes 'd = √' in red handwriting, completing it as 'd = √(a² + b² + h²)' and substituting the values '1.2² + 1.5² + 1.3²'.

  3. 5:00 – 7:34 05:00-07:34

    The instructor completes the longest diagonal calculation, showing 'd = √1.49' with a note and a circled value under the radical sign, arriving at an answer of 2.23 cm from the options. The slide then switches to a new topic titled 'Cube Surface Area to Diagonal', stating the surface area is '13.5 m²'. A red-boxed formula 'S = 6a²' is displayed, with step-by-step work computing 'a² = 13.5/6 = 2.25' and a circled value of '1.5'. This section demonstrates how to find the side length from surface area, which can then be used to calculate the diagonal of a cube.

The lecture progresses from theoretical rules about cutting cuboids to practical applications involving diagonals and surface area. The first part establishes foundational formulas for pieces and cuts, using visual aids like grids to make abstract concepts concrete. The transition to diagonal calculation shows how these geometric principles apply to real problems, with a clear worked example demonstrating the formula d = √(a² + b² + h²). The final section on surface area to diagonal extends the learning by showing how one property (surface area) can be used to find another (side length, and subsequently diagonal). The teaching style combines on-screen text formulas with handwritten annotations, creating a layered explanation that reinforces key concepts through multiple representations. The use of specific numerical examples helps students see how the general rules apply to concrete problems.

Loading lesson…