It is important to remember that your father's aggression is not directly aimed at you but is part of his illness. It is common for people who have Alzheimer's disease to pass through a phase of being angry and sometimes aggressive.
Although this phase will pass, it may help you in the meantime to consider some of the things that may be triggering your father's anger. For example, he may not like being forced to accept help to do things that he used to do on his own, such as washing. Or perhaps he feels frustrated simply because he is unable to do certain things. Another possibility is that your father is bewildered and frightened because he no longer understands what is going on around him. It is also possible that he is just bored or has an excess of energy. Sometimes hunger, the need to pass urine or constipation can lead to disruptive behaviour. If the angry outbursts have only started recently, they may be due to an infection or pain. Once you have been able to identify some of the things that tend to make your father angry, you may be able to reduce the number of angry outbursts.
Contact the Alzheimer association in your country for more advice on how to cope with challenging behaviour.