' a quartercircle

' a ″ | ' a arcmin | ' a mil | ' a mrad | ' a g | ' a grad | ' a ° | ' a point | ' a sign | ' a rad | ' a Sextant | ' a Quadrant | ' a Rt Angle | ' a quartercircle | ' a semicircle | ' a cyc | ' a r | ' a circle | ' a turn