KöMaL 2024 B5367

$a)$ In the open unit disk we place two open line segments of length $\ell$ with no common points, perpendicularly to each other. What can be the value of $\ell$? $b)$ In the open unit ball we place three line segments of length $\ell$ such that any two are disjoint (have no common points) and perpendicular to each other. What can be the value of $\ell$?