Answer
$$1 + 0i$$
Work Step by Step
$$\eqalign{
& \operatorname{cis} \left( { - 1000^\circ } \right) \cdot \operatorname{cis} \left( {1000^\circ } \right) \cr
& = \operatorname{cis} \left( { - 1000^\circ + 1000^\circ } \right) \cr
& = \operatorname{cis} \left( {0^\circ } \right) \cr
& = \cos 0^\circ + i\sin 0^\circ \cr
& = 1 + 0i \cr} $$
