Question

What 3-dimensional shape is formed when the right triangle ABC is rotated 360° about its side AC?

Answer 1

the answer to your question would be a cone

Answer 2

When a triangle ABC is rotated by 360° by it's side AC having angle ∠C=90°, we get the shape of a cone.

If ∠B=90°, then the right triangle ABC is rotated 360° about its side AC we get the shape of a Two cones attached with each other.