Answer:
16 meters
Explanation:
Area of a circle = πr²
Diameter of a circle = 2 x r 
where r = radius 
If area of the circle is given, the radius can be determined by finding the square root of the area 
64 πm² = πr²
r² = 64 πm²
r = √64
r = 8m 
diameter = 8 x 2 = 16m