Don't say any "lines". Ask her out for coffee and to study at the same time. Go to the starbucks or something. If that goes well. Ask her out on a more real "date". Take that one easy to.
IF a girl likes you "in that way" believe me you'll know. If not, you're still hanging out with a hot chick and that is a PLUS any way you slice it.
But if you like her, you'll show her just by being forward and assertive by asking her out. You don't really need to tell her how much you like her or anything on the first couple of dates. It's obvious you do or else you wouldn't be taking her out on a date. Girls don't like desperation, so don't make it seem like you're suffereing from that.
If all else fails, show her YOUR BIG PENIS. That'll get her attention right away. You can skip all the bullshit and get strait to the good stuff.