• None



Figure 1: The graph of a function of 1 variable.

There are many ways to describe a curve. Consider the following descriptions:

  • the unit circle;
  • $x^2+y^2=1$;
  • $y=\sqrt{1-x^2}$;
  • $r=1$;
  • $x=\cos\phi$, $y=\sin\phi$;
  • $\rr(\phi)=\cos\phi\,\xhat+\sin\phi\,\yhat$;
all of which describe (pieces of) the same curve. Here are some more:
  • The graph of $y=x^2$;
  • The figure shown at the right.
Which representation is best for a given problem depends on the circumstances.

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