LENGTH OF SIDE OF EQUILATERAL TRIANGLE

How do calculate the length of the side of the equilateral triangle with a circle of diameter 4meter?
The height of the triangle will be (3/2)x4 m=6m
and if side =x m,

x²-(x/2)²=6²

x²-x²/4=36

3x²/4=36

x²=(36x4)/3=48

x=4 .root3=4x1.732=6.928

 So length of side = 6.928m