C'est la Tangente que je Préfère is a 1997 French drama directed by Charlotte Silvera in which Sabine, a 15-year-old mathematical prodigy living in poverty with her welfare-dependent, gambling-addicted parents, spots Jiri — a charming, cultured theatre man from Prague in his forties — on a bus one morning and is immediately consumed by him. The two fall into a passionate and explicitly erotic relationship, with Sabine using the language of mathematics to understand and articulate her feelings — her "derivative turning negative" when he is away, her world restructured entirely around him — as the film tracks how this forbidden age-gap affair slowly transforms her suffocating, hopeless life into something with meaning and direction