Because your request didn't specify a grade level or author, here are the most common workbooks and where to find their solutions:
(e.g., Atanasyan, Merzlyak, or Pogorelov) gdz k tetradi po geometrii klass
The phrase (GDZ k tetradi po geometrii [number] klass) refers to готовые домашние задания (ready-made homework assignments) or answer keys for geometry workbooks in Russian schools . Because your request didn't specify a grade level