This is a geometric problem where two identical right triangles are inscribed within a rectangle. Let's analyze the given information and solve for unknowns based on the problem:

Given:

1. The length of the rectangle's base is $20$.
2. The height of the rectangle is $b$ (to be determined or used in calculations).
3. Each triangle has:
   • A base of $5$.
   • One angle marked as $\alpha$, and the triangle is a right triangle.

We will need to calculate or verify various parameters such as:

• Dimensions of the rectangle.
• Properties of the triangles.
• Relationships between $b$, $\alpha$, and the dimensions.

Can you confirm what specific question you'd like to solve, e.g., finding $b$, finding the area, or determining angle $\alpha$? Let me know!