Mathematics

Problem

Find all values of

x

that satisfy

\cos x = -\dfrac{1}{2}

in the interval

0 \le x < 2\pi

. a)

\left\{\dfrac{5\pi}{6},\,\dfrac{11\pi}{6}\right\}

\left\{\dfrac{2\pi}{3},\,\dfrac{4\pi}{3}\right\}

\left\{\dfrac{\pi}{3},\,\dfrac{5\pi}{3}\right\}

\left\{\dfrac{7\pi}{6},\,\dfrac{11\pi}{6}\right\}