keeping in mind that, angles are measured counter-clockwise, namely in the opposite direction of a clock, if you have a clock, notice the seconds hand how it moves, well, counter to that is going backwards, but that's how angles are regularly measured.
now, a full rotation, namely a "revolution", is a full go-around the circle, that'd be 360°, now if you 4 times around, that be 4*360 or 1440°, and if you go an extra 0.5 or half a circle, that'd be 180°, that will land us on 1440° + 180°.
