This is kind of an ambiguous question. So I will do the best I can at answering. Why is your "friend" showing you these pictures? Is your friend jealous or looking out for you? What are the intentions of this friend? Also, could it be a Photoshoped picture? Secondly, if it IS a picture of this girl you just asked out how does that make you feel that she sends out pictures like that? Are you just a toy for her to play with? How serious is she that she wants to date you? Could she have dated your friend and this is blackmail pictures? Do you practice a religion where this is not appropriate behavior before marriage? If not then my question still stands, how do you feel about pictures like that floating around? Thirdly, you said "should I give her a chance?" But you already asked her out. Are you able to date a girl with a past? Could you let the past truly BE in the past?
There are so many different parts to this question. But what it all boils down to is, what you think and feel.