1.The principal value of sin−1(−12)\sin^{-1} \left(-\frac{1}{2}\right)sin−1(−21) isa.π3\frac{\pi}{3}3πb.π6\frac{\pi}{6}6πc.−π3-\frac{\pi}{3}−3πd.−π6-\frac{\pi}{6}−6πLogin to continueOnly logged in users canattempt or see the solution.