Quote:
Originally Posted by ESRogs
The inequality a^2 <= x1^2 + x2^2 <= b^2 in question 10 implies
1) that the points have to be outside of the smaller circle and inside the larger circle, and
2) that the circles have to be centered at the origin.
Is that correct?

Correct. To be exact about inside and and outside, the perimeters of the inner circle and the outer circle are included in the region.