Class X Mathematics

Chapter 11: Areas Related to Circles

Standard NCERT & CBSE aligned study curriculum. Master concepts, track accuracy, revise weak areas, and challenge yourself with 9 customized practice modes.

Chapter Overview

Welcome to Class X Mathematics: Areas Related to Circles. This chapter forms a core structural component of the math syllabus, designed to build analytical rigor and key formula models.

Use the detailed subtopic guide below to review standard definitions, key mathematical rules, and study guidelines.

Prerequisite Concepts

Perimeter and AreaCircles

Detailed Subtopics Study Guide

Review detailed conceptual explanations, mathematical equations, and guidelines for each subtopic in this chapter:

1Perimeter and Area of circle review

Concept Explanation

The perimeter of a circle is called its circumference. The area of a circle measures the flat 2D region enclosed by it. Both are calculated using the radius r.

Mathematical Representation
C = 2\pi r, \quad A = \pi r^2
Study Guideline: If the diameter d is given, divide it by 2 first to get the radius r before calculating.

2Area of sector of a circle

Concept Explanation

A sector is the region bounded by two radii and an arc of a circle. The area of a sector with angle θ (in degrees) is calculated as a fraction of the total area of the circle.

Mathematical Representation
\text{Area of Sector} = \frac{\theta}{360^\circ} \times \pi r^2
Study Guideline: Identify the sector angle θ. The remaining area is the major sector, with angle (360° - θ).

3Area of segment of a circle

Concept Explanation

A segment is the region bounded by a chord and an arc of a circle. The area of a minor segment is calculated by subtracting the area of the corresponding triangle from the area of the sector.

Mathematical Representation
\text{Area of Segment} = \text{Area of Sector} - \text{Area of } \triangle AOB = \frac{\theta}{360^\circ}\pi r^2 - \frac{1}{2}r^2\sin\theta
Study Guideline: For θ = 90°, the triangle is right-angled (Area = 0.5 * r²). For θ = 60°, the triangle is equilateral (Area = (√3/4) * r²).

4Areas of combinations of plane figures

Concept Explanation

Calculating the area of combinations of plane figures involves finding the area of shaded regions formed by combining circles, sectors, triangles, squares, and rectangles.

Mathematical Representation
\text{Shaded Area} = \text{Area}_{\text{Outer}} - \text{Area}_{\text{Inner}} \quad \text{or sum of individual areas}
Study Guideline: Identify the basic geometric shapes that make up the figure. Work out the dimensions of each shape, compute their areas, and add or subtract as needed.