standard_description: Identify the shapes of two-dimensional cross-sections of three-dimensional objects, and identify three-dimensional objects generated by rotations of two-dimensional objects.
problem_activity: Circle
$$A$$
is shown below.
[IMG]
Draw two diameters of the circle.
Identify the shape defined by the end points of the two diameters.
Explain why this shape is always the result.


aligns: no