Hi guys, I am currently studying a basic college physics course at a university in New Zealand. The course is only going over what we were taught in college so far. I came across a practice problem and was unsure how to go about solving it. So I looked up my lecturers online notes and I believe he has made a mistake, I would like someone to confirm whether I am correct. [PLAIN]http://img192.imageshack.us/img192/84/17681455.png [Broken] I am only interested in the reaction force equation he has given, his trig manipulation seems to be the problem, someone please check the picture and confirm whether it is incorrect or correct.