arcs DC + CB + BA, are 30 + 45 + 120 respectively
so, those arcs make up 30+45+120, 195°, arc DEA, picks up the slack from the circle. A circle has a total of 360°, so DEA is just 360 - 195
now, that's in degrees, the choices there are in radians... so, to convert degrees to radians [tex]\bf Radians=\cfrac{\theta \cdot \pi }{180}\qquad \theta=\textit{angle in degrees}[/tex]
