Do u know how many relation prophet had with muawiya (RA )?

Question

Edit:

If he was not a muslim,Why Hasan (RA) being an infallible IMAM apointed by Allah ,agreed on his khilafah

Answer 1

I dont know any blood relation but Hazrat Muawiya Radi Allah Anhu was companion of Holy Prophet Peace Be Upon Him.

Yazeed bin Muawiya and Son of Hazrat Nuh are similar examples.  

Answer 2

His Brother in Law.

His companion

that's what i know  

Answer 3

Muawiyah and the Holy Prophet had Abd Manaf as their common ancestor.The Holy Prophet was the son of Abdullah who was the son of Abdul Muttalib, who was the son of Hashim who was the son of Abd Manaf. Muawiyah was the son of Abu Sufiyan, who was the son of Harb, who was the son of Umayyah, who was the son of Abd Shams, who was the son Abd Manaf. Hashim and Abd Shams were the two sons of Abd Manaf. The Holy Prophet was a descendant of Hashim while Muawiyah was a descendant of Abd Shams. Umayyah the son of Abd Shams was an important man of the line, and his descendants came to be known after him as the Umayyads.

After conversion to Islam, Muawiyah acted for some time as a Secretary to the Holy Prophet. During the caliphate of Abu Bakr and Umar, Muawiyah and his elder brother Abu Yazid fought against the Byzantines in Syria !!