Question

when turned about its axis of rotation, which shape could have created this three - dimensional object?

Explanation:

Step1: Recall 3 - D solid formation by rotation

When a 2 - D shape is rotated about an axis, it forms a 3 - D solid. A cone is formed by rotating a right - angled triangle about one of its legs. A sphere is formed by rotating a semi - circle about its diameter.

Step2: Analyze the given 3 - D object

The given 3 - D object appears to be a combination of two cones joined at their bases. A triangle, when rotated about an axis passing through its altitude, can form a cone. If we consider two congruent right - angled triangles sharing the same altitude and rotated about that common altitude, we can get the given 3 - D shape.

Answer:

A triangle (specifically, two congruent right - angled triangles sharing an altitude)