A regular decagon has all its interior angles equal. What is the measure of each interior angle of a regular decagon? Choose the correct answer.

Which statement best defines an angle in standard position?

Given a circle with center $O$ and points $Q$, $S$, and $R$ on the circumference such that angle $QOR$ is $60°$, what is the measure of arc $QSR$ in degrees?

Given that angle $tsu$ is in standard position and its terminal side passes through the point $(0,1)$ on the unit circle, what is the measure of angle $tsu$ in degrees?

If an angle $c$ in standard position has its terminal side passing through the point $(1,1)$ in the first quadrant, what is the measure of angle $c$ in degrees?

Angles $a$ and $b$ are supplementary. If angle $a$ has a measure of $80°$, what is the measure of angle $b$?

In the context of angles in standard position, if point C is at $(0,0)$, point O is at $(1,0)$, and point A is at $(0,1)$, what is the measure of angle COA in degrees?

In the context of angles in standard position, which of the following pairs of angles are considered vertical angles?