Physics
posted by Me .
This question was posted earlier but the explanation given was confusing.
The three 500 g masses in the daigram are connected by massless, rigid rods to form a triangle. What is the triangle's rotational energy (in J) if it rotates at 1.50 rev/s about an axis through the center?
(Diagram shows equilateral triangle with 500g masses at each point, the distance from point to point is 40cm and it has three 60deg angles [equilateral])

find the distance from the corner to the center of the square.
moment of intertia= 3*massoncorner*distance^2
energy: 1/2 Momentinertia*(1.50*2PI)^2 
It still did not come out correctly
I took cos60=.2/x and got .4 for the distance then did 3*.5*(.4)^2 and got .24 and then did 1/2(.24)(9.42)^2 and got 10.66J which is incorrect... 
nevermind I forgot the divide the angle...thanks!