Help me on calculating the area of the shaded part

Answer:
[tex]1051 .55 {mm}^{2} [/tex]
Step-by-step explanation:
Find the area of the square - area of 4 sectors
We'll use the formula to find one sector area
[tex]a = \frac{1}{2} \times {r}^{2} \times x[/tex]
where r is the radius of one sector and x is the angle in radians
Since each angle is in a square, the angle of the sectors is 90 degrees.
Convert degrees to radians
[tex]90 = \frac{1}{2} \pi \: rad[/tex]
The radius of one sector is given by 70mm/2=35mm
One sector area:
[tex] \frac{1}{2} \times {35}^{2} \times \frac{1}{2} \pi = 306.25\pi[/tex]
Area of all 4 sectors:
[tex]4 \times 306.25\pi = 1225\pi[/tex]
Area of the square:
[tex]70 \times 70 = 4900[/tex]
Hence, Area of square - 4 Sectors:
[tex]4900 - 1225\pi = 1051.55 {mm}^{2} (2dp)[/tex]
Answer:
1053.50 mm^2
Explanation:
first calculate the area of square ABCD
area of ABCD = AB × AB
= 70 × 70 = 4900 mm^2
if you look closely, there are 4 quater-circles with radius (AB/2 = 35 mm) and their center A,B,C and D.
now
area of any one quater circle =( pi × r^2 )/4
area of 4 quater circle =(pi × r^2)
where, pi = 3.14 and r = radius of quater circle
area of 4 quater-circle = (3.14 × 35^2)= 3846.50 mm^2
hence area of shaded region = area of square - area of 4 quater circles
= 4900 - 3846.50
=1053.50 mm^2