Question: Plot decoration with text marks

Hello,

tryning to put some text on plots,

and wonder how can I separate text decoration of variables.

For example a circule with radius

and center in

, 

So I do: 

with(plots): 

plotCircule := plot([x[0]+r[0]*sin(t), y[0]+r[0]*cos(t), t = -Pi .. Pi]) :

plotRadius := arrow({[[x[0], y[0]], [r[0]*cos((1/4)*Pi), r[0]*sin((1/4)*Pi)]]}, shape = arrow):

plotTags := textplot([[x[0], y[0], ('typeset')(C[0])], 
    [x[0]+r[0]*cos((1/4)*Pi), y[0]+r[0]*sin((1/4)*Pi), ('typeset')(R[0])]],
    'align' = {'above', 'right'}):

display({ plotCircule,  plotRadius,  plotTags});

To get (x[0]:=1; y[0]:=1; r[0]:=1; for example):

It looks pretty nice, but I would like to make more descriptive marks x[0],y[0], r[0] (with index in the lower index :) like in C[0] R[0] case on the plot above) instead of C[0] and R[0]. But if I type them in command 'textplot', it will print the values of the corresponding variables, not text marks.

Please help if you know how :)