Add Math Proving Identities of Trigonometry are a constant worry of students. So, we'll try to include more of such sums for students to practice. Free downloads of the questions with answers can be found here and for our lessons, please send a message to +65 87870198. First thing to do, memorise all the identities given to you. Yes, memorise it. Yes, it is in the formula sheet provided in the GCE O levels. But,