300°-720°
We can defined an angle as the amount of turn you get when you rotate one line so it lies on the top of another line having the same common point called the vertex. Coterminal angles are angles that differ by a whole number of complete rotations, that is, they have the common terminal side. In this way:
300° - 720° = -420°
Let's analyze the angle -420°, that is the same as a 60° angle because:
-420° + 360° = -60°
But -60° has the same terminal side as 300°, therefore the expression 300° - 720° find the measure of an angle that is coterminal with a 300° angle.
