Evaluate the following expressions. Your answer must be an angle -\pi / 2 \leq \theta \leq \pi \text { in radians. } \sin ^{-1}\mleft(\frac{1}{2}\mright)= \sin ^{-1}\mleft(-\frac{\sqrt{2}}{2}\mright)= \cos ^{-1}\mleft(\frac{\sqrt{2}}{2}\mright)= \cos ^{-1}\mleft(-\frac{\sqrt{2}}{2}\mright)=