The image you've uploaded contains a question in Thai. Here's the translation and mathematical context:

Translation:

• The question asks about angle construction.
• It shows three diagrams depicting the steps to construct an angle.
• The question is: "The basic construction shown represents the construction of an angle of what size?"

Answer choices:

1. $30^\circ$
2. $45^\circ$
3. $60^\circ$
4. $90^\circ$

Solution:

Based on the construction shown in the diagrams:

1. The first diagram depicts a straight line and a semicircle.
2. The second diagram shows an arc being drawn from the center of the semicircle, and the midpoint is located.
3. The third diagram shows the construction of an angle by intersecting the arcs.

This construction method matches the classical geometric process for creating a 90-degree angle using a compass and straightedge.

Thus, the correct answer is: 4) $90^\circ$

Would you like further details on geometric construction or explanations of the process?

Here are five related questions to explore further:

1. How is a 60-degree angle constructed using a compass and straightedge?
2. What is the process for constructing an equilateral triangle?
3. How do you bisect an angle geometrically?
4. Can you describe the steps to construct a 45-degree angle?
5. What other tools are used in classical geometry for construction?

Tip: Understanding how to use a compass and straightedge effectively can help in solving many geometric problems, especially in angle construction.