Answer:
The area of the element is approximately 19314.164 square milimeters.
Explanation:
We proceed to calculate the area highlighted on image:
1) Calculate the area of the square:
![A_(\square) = (300\,mm)^(2)](https://img.qammunity.org/2022/formulas/mathematics/high-school/zsgq7t9y95xv5zrsz0zuolu2ttq0qplekc.png)
![A_(\square) = 90000\,mm^(2)](https://img.qammunity.org/2022/formulas/mathematics/high-school/xfgprh5kenaalf6obxsjmdhq89c47af56k.png)
2) Calculate the area of each circle section:
![A_(sc) = (\pi)/(4)\cdot (150\,mm)^(2)](https://img.qammunity.org/2022/formulas/mathematics/high-school/fgkayya935jnhqiypzvgpymg0shl2pvhqi.png)
![A_(sc) = 17671.459\,mm^(2)](https://img.qammunity.org/2022/formulas/mathematics/high-school/nh3jinozw9n82nmelkujd24zl2sfponsj3.png)
3) Subtract the areas found in 2) from the area found in 1):
![A = A_(\square)-4\cdot A_(sc)](https://img.qammunity.org/2022/formulas/mathematics/high-school/brdnkdyb9j8tfobvow5tlyno2g5s7pbwyf.png)
![A = 19314.164\,mm^(2)](https://img.qammunity.org/2022/formulas/mathematics/high-school/fkbr9guz4csa8ggmv6qyw33mek3anrqhmd.png)