1. The problem statement, all variables and given/known data Please see below... 2. Relevant equations Please see below... 3. The attempt at a solution Hi. This question is on geometry with circle and triangle. I am stuck only on 2 parts of the solution and not the whole solution... Thank you.... http://img256.imageshack.us/img256/9475/gtewp249no24.jpg [Broken] [ How did they get this? They never explained or proved this and it is NOT obvious from the picture. Blue: How is that implication true? By what theorem or reasoning?