I attached an image of the problem I am currently working on. I am having a hard time understanding when to use cosine or sine when referring to the sum of the forces in the y direction or x direction. I have a general understanding as to where you initially place your coordinate system. If you take a look at the solution you will see that the sum of the forces in the y direction uses cos25, instead of my initial reaction to use sin25. If anyone can help with visual examples of different situations that would be amazing. I understand doing that would be a lot of work so any advice is also much appreciated. Thank you so much!