Compulsory one is more difficult, mainly function, and there are many problems that I don't understand very well, such as finding the range of function values.
Compulsory two is mainly solid geometry and circle and straight line. The first part contains many formulas, which is more important than memory. Straight lines and circles seem simple, with many contents, such as straight line system, tangent equation and so on.
Compulsory three is relatively simple, mainly procedures and statistics, probability But if you don't study hard, the program will still confuse you.
Compulsory four are trigonometric functions and vectors, as well as trigonometric identity transformation. The last part is relatively difficult.
In short, senior one must study mathematics seriously and lay a good foundation, otherwise he will feel that he has never learned anything in senior three.