Mr. Giuseppe Cammarata at the Liceo Scientifico Statale Benedetto Croce in Palermo, Italy is using this material in his Course IV F. Many of the solutions below were written by his students.

1. We impose in cases (a) and (b). Also impose so

a)

N.B. These are equations of the third degree, then they must have three solutions which, as regards trigonometric functions are produced by periodicity. Replacing different values of k we can find the solutions of the equation

(b)

so gives us

(c) Let x = 2y and in this case we impose so

Now gives us

Solution by Denada Rrushi and Stefania Cuccia
Liceo Scientifico Statale Benedetto Croce, May 2001.

9. Using the formulas of addition for cosine and sine,

and

impose and and replace them in the equalities above. We now have

Solution by Laura Marretta and Candido Zacchino
Liceo Scientifico Statale Benedetto Croce, May 2001.