Carcass wrote:
Point O is the center of the semicircle. If ∠ BCO = 30 ° and \(BC = 6 \sqrt{3}\) what is the area of triangle ABO?
Attachment:
GRE exam - Point O is the center of the semicircle..jpg
A. \(4 \sqrt{3}\)
B. \(6 \sqrt{3}\)
C. \(9 \sqrt{3}\)
D. \(12 \sqrt{3}\)
E. \(24 \sqrt{3}\)
triangle ABC is a right angled triangle at A, and ∠ BCO = 30 °, so ABC is 30-60-90 triangle and sides are in ratio 1:\(\sqrt{3}\):2
now opposite 60 is side \(BC = 6 \sqrt{3}\), so AB=6 and AC=12=2*radius.... radius = 6
Let us see OAB..
As we can see AB=6 and OA=OB=radius=6
so it is an equilateral triangle with side 6..
area = \((\sqrt{3}/4)*6^2=9\sqrt{3}\)
C