how did vegeta know of gotenks?

just as the title says it is implied in the fight with kid buu he know`s who gotenks was

@szlafkey: He saw him from other world. Same way he saw goku go ssj3

@lettsplay10: but then how did he not know bulma was killed and gotenks absorbed

@szlafkey: goku told him

@midnightdragon18: no i mean should he not have know that already?

@szlafkey: considering he was dead, no.

@midnightdragon18: but he was watching from other world