Question

 A circle of radius x has an equilateral triangle in it of side 9cm.Find the radius ...???

Answer 1

Circumcircle radius (R) = x cm

s=27/2
 area =sqrt(1230.18)= 35.07    {area = Sqrt(s(s-a)(s-b)(s-c)}
abc/4(area) = R

R=x=729/4(35.07)= 5.19 cm approx

Answer 2

So easy.. We know eqularteral traingle has angle of 60 so when radius is draw it bisect now angle is 30. here is figure solve it for x and you will get radius