ANSWER -
The formula for the circumference of a circle is given by C = 2πr, where r is the radius of the circle. To find the circumference, we need to first find the radius of the circle. The diameter of the circle is 2 km, so the radius can be calculated as:
r = d/2 = 2 km / 2 = 1 km
Now that we have the radius, we can use the formula to find the circumference:
C = 2πr = 2 * 3.14 * 1 km = 6.28 km