Try dragging the point on the right to change the center. Here points are given by complex numbers:

'Center'=1+1*i

The circle is constructed as the locus of all points p at an equal distance, R, from Center.

p=x+i*y

abs('Center'-p)=R

R=slider([0,4])

The following equation is just for the label.

z='Center','label'=

Graph of the formula

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