Üçgen Video Çözüm is a free Android app developed by FERNUS EĞİTİM TEKNOLOJİLERİ A.Ş. The app is designed to provide video solutions to all the questions in a book, making it an excellent reference tool for students.

The app is easy to use and provides solutions to all the questions in the book. The missing questions are updated in the app as they are completed. This makes it an excellent resource for students who want to learn and understand the concepts in the book. The app is available for free and can be downloaded from the Google Play Store.

Overall, Üçgen Video Çözüm is an excellent app for students who want to improve their understanding of the subject. The app is easy to use and provides comprehensive solutions to all the questions in the book. The fact that it's free makes it even more appealing to students who are on a tight budget.