Before revision: In this paper we present invariants of the 1d family of 3-periodics (triangular orbits) in an Elliptic Billiard (EB) , previously mentioned [ 14 ], including: (i) explicit Expressions classic invariants: perimeter and Joachimsthal's quantity;
After revision: In this paper we present invariants of the 1d family of 3-periodics (triangular orbits) in an Elliptic Billiard (EB) were introduced in [ 14 ], including: (i) explicit Expressions classic invariants: perimeter and Joachimsthal's quantity;