Please find all the points lying inside the donut x^2+y^2=9 and x^2+y^2=36?

Question

MathenaMathe questions

Answer 1

You have two circles centered at the origin.  The inner circle has a radius of 3; the outer circle has a radius of 6.  Let S be the set of points, (x,y), inside the ring defined by the two circles but not on the ring:

 

S = {(x,y) | 9 < x² + y² <  36}