How do you graph f(x)=sqrt(a^2-x^2)?

how do you graph f(x)=0, if x is rational and f(x)=1, if x is irrational?

I need to know how to graph them by hand, not on a calculator. Thanks in advance.

You can only graph it from x=-a to x=a.

if f(x)=0, then x=+-a. What does it matter if x is irrational or rational? If you are plotting it, the pencil point you make covers many rational and irrational values of x.