Answer
$$\sin \left( { - {{123}^ \circ }} \right) \approx - 0.8386$$
Work Step by Step
$$\eqalign{
& \sin \left( { - {{123}^ \circ }} \right) \cr
& {\text{using a calculator to find the value }}\left( {{\text{set the calculator in degree mode}}} \right) \cr
& {\text{then}}{\text{, we obain}} \cr
& \sin \left( { - {{123}^ \circ }} \right) \approx - 0.8386 \cr} $$