Find the value of $\cos \left(300°\right)$.

Find the values of other five trigonometric functions for the following:

$\cos \theta =-\frac{1}{2},\theta$ lies in the III quadrant

Find the values of other five trigonometric functions for the following:

$\cos \theta =\frac{2}{3},\theta$ lies in the $\mathrm{I}$ quadrant.

Find the values of other five trigonometric functions for the following:

$\sin \theta =-\frac{2}{3},\theta$ lies in the IV quadrant.