An equilateral triangle with sides of length 6 is inscribed in a circle. What is the diameter of the Circle?

A:5.2

B:6

C:6.9

D:7.5

Sin60 = (s/2) / (d/2) where s=side of triangle and d=diameter of circle

sin60=s/d

√ (3/4) = s/d

d=s/√ (3/4)

d=s√ (4/3)

d=2s/√3 and since s=6

d=12/√3

d=√48

d≈6.9282

d≈6.9 units (to the nearest tenth of a unit)