Plot a centered circle
R, 74 70 68 65 54 bytes
Edit: -11 bytes thanks to Giuseppe

function(r)plot(r*1i^(1:1e3/99),,&quot;l&quot;,l&lt;-c(-r-5,r+5),l)

Try it at rdrr.io
I propose 3 possible answers to this challenge in R, of decreasing length but with increasing caveats.
My favourite answer (above, using plot) is the middle shortest one of the 3.  It plots a circle by calculating the complex coordinates of powers of i, using 396 points (with a bit of wrap-around).  Here's an image of the output from plot_circle(5):


For a 'true' circle (rather than an almost-circle with tiny straight-lines connecting the data points), we can use the curve function with a formula, but unfortunately we need to draw the positive &amp; negative halves separately, so it ends up longer:
R, 86 84 bytes

function(r){curve((r^2-x^2)^.5,xli=l&lt;-c(-r-5,r+5),yli=l)
curve(-(r^2-x^2)^.5,add=T)}

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The shortest (that I can think of) Previously the shortest, but - thanks to Giuseppe now no longer so - is to use the circles option of the symbols function, for only 56 bytes.  However, this has the caveat that the circle symbols are always circular even if the plot is re-sized, and so may no-longer line-up with the y-axis.
R, 62 58 56 bytes

function(r)symbols(x=1,c=r,i=F,xli=l&lt;-c(-r-4,r+6),yli=l)

Try it at rdrr.io