Answer:
the set of elements that are common to each of the given sets
Step-by-step explanation:
we know the x-intercept of the line is 1, recall that an x-intercept is when the graph intercepts or touches the x-axis, and when that happens, y = 0, so the point is really x = 1, y = 0, namely (1,0). We also know another point on the line, is (-2, 9).

The circumference when the diameter is 18 = 18pi
The circumference when the diameter is 6 = 6pi
18pi/6pi=3
The circumference will become a third of what it was.
Hope this helps!