The image shows a right triangle that is being rotated about a horizontal line. The question asks what solid is generated when this right triangle is rotated about the line.

When a right triangle is rotated around its base (as shown in the diagram), the shape formed is a cone. This is because the slanted side of the triangle (the hypotenuse) generates a curved surface, and the base of the triangle becomes the circular base of the cone.

Therefore, the correct answer is:

• Cone

Would you like more details on why the cone is formed or any other aspect of the rotation?

Here are 5 questions related to this problem:

1. What solid is formed when a semicircle is rotated about its diameter?
2. How is the volume of a cone calculated?
3. What happens if a rectangle is rotated about one of its sides?
4. Can you generate a cylinder from rotating a triangle?
5. How does the axis of rotation affect the type of solid generated?

Tip: Visualizing the rotation of shapes in 3D can help you better understand the resulting solid geometry.