Question

conversation on your friend could not get selected to represt the school at the group annual dance/ competition she/he has become rude with all the other participants and the dance teachers

Answer 1

She is very angry because  she wasn't able to participate in the competition. She is very sad as she alone is not able to represent the school at the group annual dance competition.She is feeling inferior to her fellow participants and she is angry with the dance teachers as they have not given chance to her.
           I would advise her not to feel sad. I would advise her to practice more dance steps so that she could get a chance next time.