NCERT Class 7 Mathematics Ganita Prakash-II: Chapter 1 — Geometric Twins
This chapter introduces the concept of congruent figures in Mathematics for Class 7 students. It begins by posing a problem of recreating a symbol from a signboard, prompting students to think about the necessary measurements. The text explains that simply knowing arm lengths like AB and BC is insufficient, as multiple figures can be constructed with the same lengths. However, including the angle between these lengths, ∠ABC, along with the two arm lengths, fixes the shape and size. Figures that are exact copies, having the same shape and size, are called congruent. Congruent figures can be superimposed exactly one over the other, even with rotation or flipping. This foundational concept is crucial for understanding geometric constructions and proofs in CBSE Mathematics.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 7 |
| Subject | Mathematics |
| Book | Ganita Prakash-II |
| Chapter | Chapter 1 — Geometric Twins |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 2 minutes |
| Word count | 325 |
Learning outcomes
- Understand the concept of congruent figures.
- Identify the measurements needed to create an exact replica of a figure.
- Recognize that congruent figures have the same shape and size.
- Learn that congruent figures can be superimposed exactly.
Vocabulary
| Word | Meaning |
|---|---|
| Congruent | Figures that are exact copies of each other or have the same shape and size. |
| Superimposed | Placed exactly over one another. |
| Replica | An exact copy. |
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Practice questions
- What does it mean for two figures to be congruent? Answer: Two figures are congruent if they are exact copies of each other, meaning they have the same shape and size.
- Are two squares with sides 5 cm and 6 cm congruent? Answer: No, because they do not have the same size (side lengths).
- What three measurements can help create an exact replica of a figure like the one shown? Answer: Two arm lengths and the angle between them.
Frequently asked questions
What is the main idea of the 'Geometric Twins' chapter?
The chapter introduces the concept of congruent figures, which are exact copies of each other in shape and size.
What measurements are needed to create an exact replica of a figure?
Two side lengths and the angle between them are sufficient to create an exact replica.
Can congruent figures be placed one over the other exactly?
Yes, congruent figures can be superimposed exactly, one over the other.
Does rotation or flipping affect congruence?
No, congruent figures can be rotated or flipped before superimposing, and they will still fit exactly.
What is the difference between having the same lengths and being congruent?
Figures can have the same lengths but different shapes (angles), so they are not necessarily congruent. Congruence requires both same shape and same size.
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Topics covered
NCERT Class 7 Mathematics — Ganita Prakash-II — Chapter 1 — Geometric Twins. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.