Answer the following questions on trigonometric equations:
(i) State the zero–product principle.
(ii) Explain why, when a trigonometric equation can be written in the form f(x)g(x)=0, the complete solution set is obtained by solving f(x)=0 and g(x)=0 separately.
(iii) Write the general solution of (a) sinx=0 and (b) cosx=0. Explain briefly how periodicity is used in writing these results.