**Areas Related to Circles**

Contents

__Area Related to Circle__

**Circumference of circle = π * Diameter = π * 2*Radius**

__Area of Circle = π * Radius * Radius = πr2__

**Numerical**: Archery target marked with its five scoring regions from the centre outwards as Gold, Red, Blue, Black and White. The diameter of the region representing Gold score is 21 cm and each of the other bands is 10.5 cm wide. Find area of each of five scoring regions.

**Solution**:**Radius of Gold Circle is 10.5 cm, thus area of gold circle = πr2**

**Or Area = π(10.5)2**

**= 346.5 cm2****Area of the red Zone = Area of red circle – Area of Gold circle**

**Or Area of red Zone = π(21)2 – π (10.5)2**

**Or Area of red zone**

**= 1039.5 cm2**** **

**Similarly you can find area of all the zones.**

__Area of Sector & Segment__

**Part of the circular region enclosed by two radii and the corresponding arc is called a sector of the circle.**

**Part of the circular region enclosed between a chord and the corresponding arc is called a segment of the circle.**

**When we write ‘segment’ and ‘sector’ we will mean the ‘minor segment’ and the ‘minor sector’ respectively, unless stated otherwise.**

__Areas of Combination of Plane figures__

**Area of figure = Sum of areas of smaller parts**

**Numerical**: From each corner of a square of side 4 cm a quadrant of a circle of radius 1 cm is cut and also a circle of diameter 2 cm is cut. Find area of remaining portion of the square.

**Solution**:**Required area = Area of Square -4 (1/4 area of circles A) – Area of circle B**

**= 4* 4 – 4* ¼ * π * 1 * 1 – π * 1 * 1 cm2**

**= 68/7 cm2**

**Also Read :**

MATHS Revision Notes

Chapter:01 Real Numbers System

Chapter:02 Polynomials

Chapter:03 Pair of Linear Equations in Two Variables

Chapter:04 Quadratic Equation

Chapter:05 Arithemetic Progressions

Chapter:06 Triangles

Chapter:07 Coordinate Geometry

Chapter:08 Introduction to Trignometry

Chapter:09 Some Application Of Trignometry

Chapter:10 Circles

Chapter:11 Constructions

Chapter:12 Area Related to Cirles

Chapter:13 Surface Area Volume

Chapter:14 Stastistics

Chapter:15 Probability