What does Austen reveal about Elizabeth when she writes that Elizabeth looked at Mr. Dracy with a ''triumphant sensation'' as soon as Mr. Bingley takes a seat next to Jane?

It tells us that Elizabeth feels she and Mr. Darcy have done well. She knows that Bingley still loves her sister and that he will make a devoted husband to such a caring girl. I think Elizabeth is also happy that Mr. Darcy shares in her same values and cares about the fortunes of her family.