\( \definecolor{colordef}{RGB}{249,49,84} \definecolor{colorprop}{RGB}{18,102,241} \)
Trouve la valeur exacte de \(\cos \theta\) si \(\sin \theta = \frac{\sqrt{2}}{2}\) et \(-\dfrac{\pi}{2} \leq \theta < \dfrac{\pi}{2}\).
\(\cos \theta =\)