Find the missing side length of a rectangle that is part of a right triangle.

The problem is asking to find the value represented by the question mark in the image.
From the image, we can see a square with a question mark inside.
The side length of the square is given as 3.
The area of a square is calculated by the formula:
Area = side side = side

In this case, the side length of the square is 3.
So, the area of the square is:
Area =

The question mark is inside the square, and it is likely asking for the area of the square, as the area is a common property to be asked for a square.

The right triangle attached to the square has sides 3, 4, and 5. This is a right-angled triangle because it satisfies the Pythagorean theorem ( ). The side of the square is also a side of the right triangle.

Therefore, the value of the question mark, which represents the area of the square, is 9.

Final Answer: The final answer is