Problem Statement
Let $h(n)$ be maximal such that in any $n$ points in $\mathbb{R}^2$ (with no three on a line and no four on a circle) there are at least $h(n)$ many circles of different radii passing through three points. Estimate $h(n)$.
Categories:
Geometry
Progress
See also [104] and [506].Source: erdosproblems.com/831 | Last verified: January 16, 2026