Final answer:
The subject of this question is Mathematics, specifically geometry and transformations. A two-dimensional shape can be created by rotating a certain shape about its base, and another shape can give the same result by rotating it about a line joining two opposite vertices.
Step-by-step explanation:
In this question, the two-dimensional shape is being created by rotating a certain shape about its base. Another way to create this shape is by rotating a different shape about a line joining two opposite vertices. These rotations are called geometric transformations.
For example, a cube can be rotated 90° around an axis perpendicular to any pair of its faces, creating a similar shape. Another way to rotate the cube is around the axes that extend between opposite corners, which requires three 120° rotations to complete a full circle. Both of these rotations result in different versions of the same shape.
So, the subject of this question is Mathematics, specifically geometry and transformations.