In Problems 1-3, sketch the indicated set. Describe the boundary of the set. Finally, state whether the set in open, closed, or neither.
1. {(x, y): 2 ( x ( 4, 1 ( y ( 5}
2. {(x, y): x2 + y2 < 5}
3. {(x, y): 0 < x2 + y2 ( 1}