Using the formulas, r=radiusC=2πr (circumference)d=2r (diameter)
So you have the diameter of the circle basically, which is the base. So the way I read this, the length doesn't matter.
Since we have diameter, and we need radius to find circumference, we need to divide it in half. So 7/2=3.5.
Now we plug that into our circumference equation, C=2πr, we have:
C=2π3.5
So π times 3.5 =10.99 Now we have
C=2(10.99) which is C=21.98