I have been using Khan academy for months now and it has been absolutely amazing! I’m in trig currently in precalculus on the app. However the videos do not always match the tests for example, Sal shows you how you get a period just by counting the points on the x axis however when tested you are asked to solve it by using the actual mathematical method. Which he teaches in another video further on past this. The hints are great for filling in these gaps at least sometimes but don’t always explain well. Right now I’m in inverse trig functions. The intro into arcsine and arccosine are great and even arctangent, but once again you are given decimal approximations instead of the radian values when tested however in the videos Sal uses radian values. It isn’t brought up in that video but is brought up in a later video on how to solve using decimal approximations. This makes the tests extremely hard and also happens for phases shifts as well. Videos aren’t always matched to the tests very well. The videos are amazing and do explain these concepts a bit too late. I went onto YouTube to a different math professor to understand phase shifts for a test only to find out for all the extra work Sal explains this in a later video. Again the videos are amazing but just seem like they are out of order once in awhile. However I have been through all of of high school level khan academy and trig seems to be the only section to do this.