Calculate the measurement of the reference angle for - 128°.

Evaluate the following expression manually by using reference angles, and applying the rule of signs of trigonometric functions.

sin (- 210°)

Determine the reference angle of 191°.

Determine all possible values of θ in the interval [0°, 360°), which have the same value as the given function value.

sin θ = -1/2

Determine the reference angle for an angle measuring $275^{\circ}$.

Determine the reference angle for an angle measuring $5.6$.

Determine the reference angle for an angle measuring $-\frac{19\pi}{5}$.