We have three squares, which sides are the same of a square triangle.
We know the area of 2 out of the 3 squares. We have to find the area of the third.
The area of the smaller square is 81. As b it is side, the area of the square is b^2=81.
The area of the biggest triangle is c^2=369.
The area we need to find has a value of a^2.
As we have a square triangle, we can apply the Pythagorean theorem:
![a^2+b^2=c^2^{}](https://img.qammunity.org/2023/formulas/mathematics/college/dmhf6nateqi4c2td40ow6mw6en6pi0pmix.png)
As we already know the values of b^2 and c^2, we can find the area of the square as:
![\text{Area}=a^2=c^2-b^2=369-81=288](https://img.qammunity.org/2023/formulas/mathematics/college/bna0i3pc5avixcui72v9qgdg9ryyauvliy.png)
Answer: the area of the square is a^2=288.