- 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
Find the area of the shaded region in the given figure, if $PQ = 24\ cm, PR = 7\ cm$ and $O$ is the centre of the circle.
"
Given :
In the given figure, $PQ=24 cm, PR=7 cm$ and $O$ is the center of the circle.
To do :
We have to find the area of the shaded region.
Solution :
Area of the shaded region $=$ Area of the semi-circle $-$ Area of $\triangle PQR$
In $\triangle PQR$,
$\angle QPR = 90°$ [Diameter subtends $90^o$ on any point on the circle]
Therefore,
$QR^2 = PQ^2+PR^2$
$QR^2 = 24^2 + 7^2$
$QR^2 = 576+49$
$QR^2 = 625$
$QR = 25 cm$
Diameter $= 25 cm$
Radius $r= \frac{25}{2} cm$
Base of triangle (b)$= 7 cm$, height (h)$= 24cm$.
Area of the shaded region $= \frac{1}{2} \pi r^2 - \frac{1}{2} \times b \times h$
$= \frac{1}{2}(\pi r^2- b \times h)$
$= \frac{1}{2}( \frac{22}{7}\times \frac{25}{2}\times \frac{25}{2}- 7 \times 24)$
$ = \frac{1}{2}(\frac{13750}{28} - 168)$
$=\frac{1}{2}(491-168)$
$= \frac{1}{2}(323)$
$ = \frac{323}{2}$
$= 161.5\ cm^2$.
Therefore, the area of the shaded region is $161.5\ cm^2$.