Area formula:
3.14*radius*radius
Substitute in numbers you already know (radius is half the diameter):
3.14*(6/2)*(6/2)
=3.14*9
=28.26
The area is 28.26 square meters.
Circumference formula:
3.14*diameter
Substitute in numbers you know:
3.14*6
=18.84
The circumference is 18.84 meters.
Hope this helped!