- Data Structure
- Networking
- RDBMS
- Operating System
- Java
- MS Excel
- iOS
- HTML
- CSS
- Android
- Python
- C Programming
- C++
- C#
- MongoDB
- MySQL
- Javascript
- PHP
- Physics
- Chemistry
- Biology
- Mathematics
- English
- Economics
- Psychology
- Social Studies
- Fashion Studies
- Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
The area of a circle is \( 616 \mathrm{~cm}^{2} \). There is a \( 2 \mathrm{~m} \) wide road on its edge. What will be area of that road?
Given:
The area of a circle is \( 616 \mathrm{~cm}^{2} \). There is a \( 2 \mathrm{~m} \) wide road on its edge.
To do:
We have to find the area of the road.
Solution:
Let the radius of the inner circle be $r$.
Width of the road $=2\ m$.
This implies,
Radius of the outer circle$=r+2\ m$.
Area of the inner circle$=616\ m^2$
Therefore,
$\pi r^2=616$
$\frac{22}{7}\times r^2=616$
$r^2=616\times\frac{7}{22}$
$r^2=28\times7$
$r^2=7\times4\times7$
$r^2=(2\times7)^2$
$r=14\ m$
Radius of the outer circle$=14+2\ m=16\ m$.
Area of the outer circle$=\pi (16)^2$
$=\frac{22}{7}\times256$
$=804.57\ m^2$
Area of the road$=$Area of the outer circle$-$ Area of the inner circle
$=804.57-616\ m^2$
$=188.57\ m^2$
The area of the road is $188.57\ m^2$.