Parameterize a union of circles

samedi 1 février 2014

1. The problem statement, all variables and given/known data

Let [itex]C=\lbrace(x,y) \in R^2: x^2+y^2=1 \rbrace \cup \lbrace (x,y) \in R^2: (x-1)^2+y^2=1 \rbrace [/itex]. Give a parameterization of the curve C.



3. The attempt at a solution

I'm not sure how valid it is but I tried to use a 'piecewise parameterisation', defining it to be [itex]r(t)=(cos(t+\frac{\pi}{6}), sin(t+\frac{\pi}{6})[/itex] for all [itex]t \in [0, 2\pi)[/itex] and [itex]r(t)=(cos(t+\frac{2\pi}{3})+1, sin(t+\frac{2\pi}{3})[/itex] for all [itex]t \in [2\pi, 4\pi][/itex].



So it traces out the first circle out at the top intersection and then the second. But I'm not sure how to make this smooth at the intersection, and one-to-one, as I'm quite sure it has to be. This is the best I could come up with.





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