Beitr\"age zur Algebra und Geometrie
Contributions to Algebra and Geometry
Volume 36 (1995), No. 1
Can You Recognize the Shape of a Figure from its Shadows?
J. Kincses and A. Kurusa
In connection with the Hammer's X-ray picture problem we discuss
the following question: Given two convex compact sets
inside a circle such that the sets subtend equal angles at each point
of the circle, is it then true that the
sets must coincide?