This app contains most of the formulas a person will need when taking trigonometry in school. In fact, it even has a couple of pages for calculus involving trig.
This app does not explain anything in detail, it just shows the formulas which is nice because the students can use this app rather than the book, once they have reached a certain level of proficiency.
So this app does exactly what the title states. It provides a reference and nothing more. I think for my students it provides a place for them to look up formulas without using the book. There is one area, this reference is light in and that involves formulas where the period, changes in height, flipping, etc but the rest of it is quite good.