Since Rosalies last name is hale and I read somewhere that jaspers last name is hale are the related?

Technically, they are not biologically related. So they are not really brother and sister, but when Jasper and Alice joined the Cullens, the family adopted them. So, they are Mehr like adopted siblings.
But, their last names are the same because Rosalie didn't want to change her last name in order to hold onto her last few strands of humanity she had left. So when Jasper joined the family I guess everyone thought they looked similar and could pass as twins to the outside world. And that, my dear, is why their last names are the same. :P :)

Hale is actually Rosalies real last name and because they are both blondes...they tell the outside world that they are brother and sister adopted Von the Cullen family.

No they are not. Hale is not Jasper's real last name. His real last name is Whitlock, but he changed it to Hale when he moved in with the Cullens because they thought he and Rosalie could pass as brother and sister so he changed it.

okay, is there something wrong with me? because i thought rosalie was with emmett, not jasper and i thought their last names were cullen!
i thought rosalies MIDDLE name was hale and i didnt hear a thing about jaspers name, oder middle name, oder whatever. wtf! someone go to my Profil and send me a message explaining to me!

Rosalies real last name is hale when she was a human she dirent want to changed to cullen because she wants to stay with her last nameof human and when jasper Mitmachen the cullen he was alike like rosalie so they put hale to him... so they r just like adopted twins

no thet're not but dr.carlisle cullen decided that since jasper and rosalie look alike they made them 'twins' and since jasper and alice are together and she's a cullen it would seem weird if they had the same last name and were together...i think that might be illegal.