The deal is confirmed to be worth €31 million and Trincao will join Barcelona in the summer.
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The forward has been compared to compatriot Cristiano Ronaldo by some and Barca reportedly had first option on him which they have now taken up.
He will sign a contract until 2025 and have a release clause of €500 million.
Barca had been linked with a move for a forward this window after Luis Suarez underwent surgery.
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They were rumoured to be after a host of names including Willian, Rodrigo and Richarlison but now reports close to the club have said there will be no players arriving in this window.