Question:
The perimeter of a certain sector of a circle of radius 5.6 m is 27.2 m. Find the area of the sector.
Solution:
We know that the area A of a sector of circle of radius r and arc length l is given by
$A=\frac{1}{2} l r$
Let OAB is the given sector. Then,
Perimeter of sector OAB = 27.2 m
OA + OB + arc AB = 27.2 m
5.6 + 5.6 + arc AB = 27.2 m
11.2 + arc AB = 27.2 m
$\operatorname{arc} \mathrm{AB}=16 \mathrm{~m}$
So, $l=16 \mathrm{~m}$
Now substituting the value of r and l in above formula,
$A=\frac{1}{2} \times 16 \times 5.6$
$=44.8 \mathrm{~m}^{2}$