Is what was uttered by the husband considered a divorce? Is it permissible to take the wife back an hour after he uttered the divorce while in a state of anger? What is the opinion of the four schools of thought on this?

Your wife is divorced. Your statement of divorce, whether made as a challenge or in a state of anger, does not invalidate it unless you were unconscious. Your saying "I will take you back into my wedlock" (أرجعك إلى عصمتي) in the present tense is not an explicit declaration of reconciliation (raj'ah), and reconciliation is not valid with it unless you intended reconciliation by it. The length of the time interval does not matter as long as the reconciliation occurs within the waiting period ('iddah). Both spouses must be careful to avoid problems and be rational in resolving them. A wife who is insolent towards her husband is considered disobedient (nashiz).