CBSE Notes Class 9 Maths Chapter 5 - I'm Up and Down, and Round and Round
These CBSE Class 9 Maths Notes Chapter 5 - "I'm Up and Down, and Round and Round" are based on the latest CBSE syllabus and the revised NCERT textbook, Ganita Manjari. They help students understand important concepts in a simple and structured manner, making it easier to revise key topics, properties, and theorems before examinations. These notes are also useful for homework, practice, and quick revision.
The Chapter "I'm Up and Down, and Round and Round" in the revised 2026-27 syllabus introduces students to circles and their parts, symmetry, equal chords, angles, arcs, and cyclic quadrilaterals. It also covers important circle properties and theorems, helping students understand geometric relationships and solve problems effectively.
1.0Download CBSE Notes Class 9 Maths Chapter 5 - I'm Up and Down, and Round and Round
Download CBSE Class 9 Maths Chapter 5 – I'm Up and Down, and Round and Round Notes to understand key concepts of circles and for quick revision, practice, homework, and exam preparation
2.0Important Concepts CBSE Notes Class 9 Maths Chapter 5 - I'm Up and Down, and Round and Round - Circles
Circle and Its Parts
A circle is a set of points that are at the same distance from a fixed point called the centre.
- Radius: Line segment from the centre to any point on the circle.
- Circumference: Boundary or perimeter of a circle.
- Chord: Line segment joining any two points on a circle.
- Diameter: A chord passing through the centre.
- Secant: A line that cuts a circle at two points.
- Tangent: A line that touches a circle at exactly one point.
Arcs and Their Types
An arc is a part of the circumference of a circle.
- Minor arc: Smaller than half of the circle.
- Major arc: Greater than half of the circle.
- Semi-circle: An arc formed when a diameter divides a circle into two equal parts.
- Congruent arcs: Arcs having the same degree measure.
Segment and Sector
- Segment: The part of a circle bounded by a chord and an arc.
- Sector: The region enclosed by an arc and its two radii.
- Quadrant: One-fourth of a circular disc.
Symmetry in a Circle
A circle has complete rotational symmetry because it looks the same after rotation through any angle. It also has reflection symmetry. Every diameter acts as a line of symmetry and divides the circle into two equal halves.
Equal Chords and Their Properties
Equal chords of a circle have equal angles at the centre. The perpendicular drawn from the centre to a chord bisects the chord. Equal chords are also at equal distances from the centre. The reverse statements are also true.
Angles in a Circle
The angle made by an arc at the centre is twice the angle made by the same arc at a point on the remaining part of the circle. Angles standing on the same segment of a circle are equal. An angle in a semi-circle is a right angle.
Cyclic Quadrilateral
A quadrilateral whose four vertices lie on the same circle is called a cyclic quadrilateral. Its opposite angles are supplementary. The reverse statement is also true: if a pair of opposite angles of a quadrilateral are supplementary, the quadrilateral is cyclic.
Exterior Angle of a Cyclic Quadrilateral
The exterior angle of a cyclic quadrilateral is equal to its interior opposite angle. This property is useful when finding unknown angles in circle-based questions.
3.0Other Study Materials for Class 9 Maths
Students can use additional study materials along with these notes, such as:
4.0Why CBSE Notes Class 9 Maths - I'm Up and Down, and Round and Round
These notes cover the main points from the chapter. Students can use them while studying, practising questions, and revising for tests.
- Easy revision: Find the main points in one place.
- Save time: Read the important topics without going through the whole chapter again.
- Study at home: Use the notes while studying on your own.
- Before practice: Read the main points before solving exercises.
- Before a test: Go through the chapter when you have less time.
- Check your work: Use the key points to check your answers.