Answer
$${\text{multiply,}}\,\,\,{\text{add}}$$
Work Step by Step
$$\eqalign{
& {\text{When multiplying two complex numbers in trigonometric form}}, \cr
& {\text{we }}\underline {{\text{multiply}}} {\text{ their absolute values and }}\underline {{\text{add}}} {\text{ their arguments}}. \cr} $$
