The image you have shared contains a truss problem with several questions related to the reactions and forces in the truss members. The problem involves calculating:

1. The vertical reaction at point D.
2. The horizontal reaction at point D.
3. The force in member AB.
4. The force in member BD.

The applied load $P$ is given as 50 kN. The system appears to be statically determinate, with given dimensions for the truss members.

To proceed, I will explain how you would typically approach solving these types of problems:

Steps to Solve:

1. Identify the Support Reactions: Use equilibrium equations (sum of forces in the horizontal and vertical directions and the sum of moments) to determine the reaction forces at the supports.

   $\Sigma F_x = 0, \quad \Sigma F_y = 0, \quad \Sigma M = 0$

2. Calculate the Vertical and Horizontal Reactions at D: For a truss supported at D (assuming it's a pin joint) and another support (likely at point A or another point), use the moment about one of the supports to solve for the vertical and horizontal components at D.

3. Determine the Force in Members: Once the reactions are known, you can proceed with the method of joints or the method of sections to find the forces in members AB, BD, and others. For instance, by isolating the joint at A or B, you can use equilibrium equations to determine the forces in those members.

Would you like to go step-by-step through these calculations, or do you need a specific part explained in more detail?

Follow-up questions to explore:

1. How do we use the method of joints to analyze trusses?
2. What is the importance of static equilibrium equations in truss analysis?
3. How would you apply the method of sections to quickly find the force in member BD?
4. Why is it important to understand the type of support (roller or pinned) when analyzing a truss?
5. Can you explain the role of zero-force members in truss analysis?

Tip:

When solving truss problems, always ensure that your structure is statically determinate by checking if the number of members and reactions is suitable for a solvable system.