Q. Determine the qualities of the given set. (Select all that apply.){(x,y)∣9<x2+y2<25}□ open□ connected□ simply-connected□ none of the above
Identify Nature of Set: Identify the nature of the set based on the inequality 9 < x^2 + y^2 < 25. This inequality describes a region between two circles centered at the origin with radii 3 and 5, respectively. The area is not inclusive of the boundaries since it's strictly greater than 9 and less than 25.
Determine Openness: Determine if the set is open.Since the set does not include the boundary points (x2+y2=9 or x2+y2=25), it is open.
Check for Connectivity: Check if the set is connected.The area between two concentric circles is a single unbroken region, hence it is connected.
Assess Simply-Connected: Assess if the set is simply-connected.A set is simply-connected if every loop in the set can be continuously contracted to a point within the set. The annular region between two circles is not simply-connected because a loop around the inner circle cannot be contracted to a point without leaving the set.