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Chapter 5 of 8
Chapter Summary

I'm Up and Down, and Round and Round

CBSE · Class 9 · Mathematics

Summary of I'm Up and Down, and Round and Round for CBSE Class 9 Mathematics. Key concepts, important points, and chapter overview.

90 questions84 flashcards5 concepts

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Overview

A circle is the set of all points on a plane that are at the same distance from one fixed point called the centre. The chapter builds the full geometry of circles from this basic idea. It explains radius, chord, diameter, arc, circumcircle, circumcentre, cyclic quadrilateral, and the major theorems

Key Concepts

A circle is the set

A circle is the set of all points equidistant from a fixed point. That fixed point is the centre, and the common distance from the centre to any point

A chord is a line segment

A chord is a line segment joining two points on a circle. A diameter is a chord passing through the centre. The diameter is the greatest chord.

An arc is a connected portion

An arc is a connected portion of a circle between two end points. If the central angle is less than 180°, the arc is minor; if it is greater than 180°

A circle has complete rotational symmetry

A circle has complete rotational symmetry: rotating it about its centre by any angle leaves it unchanged. Every diameter is a line of reflection symme

There is exactly one circle passing

There is exactly one circle passing through three non-collinear points. Its centre is the circumcentre, found at the intersection of the perpendicular

Learning Objectives

  • Understand the definition of a circle, its centre, radius, chord, diameter, and arc
  • Recognise rotational symmetry and reflection symmetry in a circle
  • Find the unique circle through three non-collinear points and locate the circumcentre
  • Use congruence to prove results about equal chords and equal angles at the centre
  • Apply perpendicular bisector properties of chords

Frequently Asked Questions

What are the important topics in I'm Up and Down, and Round and Round for CBSE Class 9 Mathematics?
I'm Up and Down, and Round and Round covers several key topics that are frequently asked in CBSE Class 9 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in I'm Up and Down, and Round and Round — CBSE Class 9 Mathematics?
Understand the core concepts first, then work through the 90 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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