In fact, only angles divisible by gcd(18,45) = 9° are reachable? No — by the linear combination: 18n - 45k = 0 → all reachable angles are multiples of 9, but specifically, since 18 and 45 share factor 9, reachable angles are multiples of 9°, but more precisely, the set is 9k , but constrained by step size. - Portal da Acústica