Triangle ABC has circumcenter O. If AB = 10 and [OAB] = 30 find the circumradius of triangle ABC.
The circumcenter is the perpendicular bisectors of a side of a triangle intersect.
cos(30)=1/2AB/x
X=1/2AB/cos(30)=5/(sqrt3/2)=10/sqrt3=5.77 units
AB = 10 [OAB] = 30 u2
AB / 2 = 5 (Midpoint on AB is M)
OM = 30 / 5 = 6
Circumradius r = sqrt(52 + 62) = √61
+40 
