Does triple divorce take effect upon the wife if the husband's brother returns to work for him, knowing that the husband uttered this during his anger, then confirmed it after he calmed down?

Anger does not prevent a divorce from taking effect as long as the person uttering it is aware of what he is saying. Swearing by divorce leads to divorce if the oath is broken. Uttering "three" effects a triple divorce, and this is the authoritative ruling. So, if the husband reinstated his brother to work, his divorce is effected as a triple divorce, and his wife becomes irrevocably divorced from him. He cannot take her back unless she marries another husband, who then divorces her or dies, and her waiting period (iddah) expires. We emphasize that the permissible oath is to swear by Allah the Almighty.