3. Execute the program flowchart shown in the figure, the output value of $S$ is\\
A. $- \frac { \sqrt { 3 } } { 2 }$ B. $\frac { \sqrt { 3 } } { 2 }$ C. $- \frac { 1 } { 2 }$ D. $\frac { 1 } { 2 }$\\
\includegraphics[max width=\textwidth, alt={}, center]{48ad8a32-6944-4c7b-b59a-73846da18c8a-1_784_469_1069_306}