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We give a family ${ℱ}_{h,\beta }$ of elliptic curves, depending on two nonzero rational parameters $\beta$ and $h$, such that the following statement holds: let $ℰ$ be an elliptic curve and let $ℰ\left[3\right]$ be its 3-torsion subgroup. This group verifies $\mathbb{Q}\left(ℰ\left[3\right]\right)=\mathbb{Q}\left({\zeta }_3\right)$ if and only if $ℰ$ belongs to ${ℱ}_{h,\beta }$ . Furthermore, we consider the problem of the local-global divisibility by 9 for points of elliptic curves. The number 9 is one of the few exceptional powers of primes, for which an answer to the local-global...