Question:
A rectangular piece is 20 m long and 15 m wide. From its four corners, quadrants of radii 3.5 m have been cut. Find the area of the remaining part.
Solution:
It is given that, the quadrants of radius r have been cut from the four corners of a rectangular piece is of length 
and width
.
We have to find the area of remaining part.
We know that,
Area of rectangle $=I \times w$
$=20 \times 15$
$=300 \mathrm{~m}^{2}$
Area of quadrant $=\frac{1}{4} \pi r^{2}$
$=\frac{1}{4} \times \frac{22}{7} \times 3.5 \times 3.5$
$=9.625 \mathrm{~m}^{2}$
Now,
Area of remaining part $=$ Area of rectangle $-4 \times$ Area of quadrant
$=300-4 \times 9.625$
$=300-38.5$
$=261.5 \mathrm{~m}^{2}$