This book is really an "aid" written to strengthen the effort of that student who wants to understand and learn the Mathematics taught in 3rd High School. For this purpose, each paragraph contains summary theory, solved exercises of group A and B and unsolved exercises with answers or hints. The exercises marked with an asterisk "*" and in general the exercises of the B' group are interesting or a little difficult and can be dealt with mainly by those who have a special interest in Mathematics.