Such a sequence could be the balls of radius i centered at the origin.

Consider an open disk of radius centered at the origin, which will represent the "still" drum head shape.

Consider a cube of side length 2d, centered at the origin.

Let be a collection of distinct points on the unit sphere centered at the origin.

Its graph is the upper semicircle centered at the origin.

An easier to understand approach is to draw an imaginary circle of radius r centered at the origin.

Refer to the illustration on the right, in which the ellipse is centered at the origin.

It is the interior of a circle of radius 1, centered at the origin.

Consider a fixed circle of radius centered at the origin.

We then choose another figure totally inside it, such as a smaller square, centred at the origin.