Area Related to Circle – Comprehensive Notes
🔵 1. Introduction to Circle
A circle is a two-dimensional geometric figure where all points are at an equal distance from a fixed point called the centre.
🔑 Key Terms
Centre (O): Fixed point inside the circle
Radius (r): Distance from centre to any point on the circle
Diameter (d): Twice the radius → d = 2r
Circumference: Boundary of the circle
Chord: Line joining any two points on the circle
Arc: Part of the circumference
Sector: Region enclosed by two radii and an arc
Segment: Region enclosed by a chord and an arc
🔵 2. Value of π (Pi)
π ≈ 3.14 or 22/7
π = (Circumference ÷ Diameter)
🔵 3. Area of a Circle
📐 Formula:
Area of Circle
=
𝜋
𝑟
2
Area of Circle=πr
2
📌 Where r = radius
📝 Example:
If r = 7 cm
Area
=
22
7
×
7
×
7
=
154
cm
2
Area=
7
22
×7×7=154 cm
2
🔵 4. Circumference of a Circle
📐 Formula:
Circumference
=
2
𝜋
𝑟
Circumference=2πr
🔵 5. Area of Semicircle
📐 Formula:
Area
=
1
2
𝜋
𝑟
2
Area=
2
1
πr
2
📐 Perimeter of Semicircle:
𝜋
𝑟
+
2
𝑟
πr+2r
🔵 6. Area of Quadrant (¼ Circle)
📐 Formula:
Area
=
1
4
𝜋
𝑟
2
Area=
4
1
πr
2
📐 Perimeter:
𝜋
𝑟
2
+
2
𝑟
2
πr
+2r
🔵 7. Area of Sector of a Circle
📐 Formula:
Area of Sector
=
𝜃
360
°
×
𝜋
𝑟
2
Area of Sector=
360°
θ
×πr
2
📌 Where θ = angle at the centre
🔵 8. Length of Arc
📐 Formula:
Arc Length
=
𝜃
360
°
×
2
𝜋
𝑟
Arc Length=
360°
θ
×2πr
🔵 9. Area of Segment of a Circle
📐 Formula:
Area of Segment
=
Area of Sector
−
Area of Triangle
Area of Segment=Area of Sector−Area of Triangle
🔵 10. Area of Annulus (Ring)
📐 Formula:
Area
=
𝜋
(
𝑅
2
−
𝑟
2
)
Area=π(R
2
−r
2
)
📌 Where R = outer radius, r = inner radius
🔵 11. Important Applications
✔ Wheels
✔ Coins
✔ Plates
✔ Circular parks
✔ Clocks
✔ Pipes and rings
🧠 Exam Tips
✔ Always write units (cm², m²)
✔ Convert diameter to radius
✔ Use correct π value
✔ Draw neat diagrams
Area of circle, circle formulas, sector of circle, segment of circle, semicircle area, quadrant area, arc length, circumference of circle, annulus area, geometry formulas, maths notes class 9, class 10 maths, CBSE maths, competitive exams maths, basic geometry
#AreaOfCircle
#CircleFormulas
#MathsNotes
#Geometry
#Class9Maths
#Class10Maths
#CBSEMaths
#CompetitiveExams
#MathsRevision
#LearnMaths
#MathsConcepts
#EducationContent
#MathsForStudents
#OnlineLearning
Child animation learning
Animated study for kids
Fun learning videos
Cartoon learning for class 1 to 5
Interactive animated education
Kids smart learning
Animated storytelling for children
Creative learning animation
Primary school animated content
Visual learning for kids
Animation for maths and science
Animated English learning
Fun classroom activities
Edutainment videos for kids
Kids study motivation animation
📜 Copyright Disclaimer
© [2025] MS CLASSES (A Unit of MS Pvt Ltd). All Rights Reserved.
All materials, including text, graphics, logos, images, notes, question papers, PDFs, and digital content, are the exclusive intellectual property of MS CLASSES (A Unit of MS Pvt Ltd) under the leadership of Ram Sir.
No part of this publication/content may be copied, reproduced, distributed, transmitted, stored, or translated into any form—electronic, mechanical, photocopying, recording, or otherwise—without prior written permission from MS CLASSES.
Fair Use Notice:
Some references or information may be used for educational, informational, or research purposes under Section 107 of the Copyright Act, 1976 (Fair Use). Such use is strictly non-commercial and intended only to promote learning.
⚠️ Warning: Unauthorized use, reproduction, sharing, or distribution of this content without permission is strictly prohibited and may invite legal action under applicable copyright laws.
Official Contact:
📞 9076904514
✉️ [email protected]
🌐 msclasses.diginweb.site
Информация по комментариям в разработке