Yes, it is. Circles that are in the same plane and having the same center are called congruent circles.
Circles in the same plane with the same center are concentric circles.
AnswerThat would be circles with different sizes, having the same center.AnswerConcentric circles have a common center and different radii.Bulls eye could be an example of concentric circles.ans; Concentric circles are nothing but 2or more circles having common center but having different radius.Source: www.icoachmath.com
No, tangent circles do not have the same center. They just touch at the side. Here is an example:
Concentric circles are circles with the same common centre.