Based on the Andreotti-Frankel theorem, what is the CW complex homotopy equivalent to $x^2 + y^2 - 1$?

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I am referring to this theorem: http://en.wikipedia.org/wiki/Andreotti%E2%80%93Frankel_theorem

I have no idea how to begin thinking about this.

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A non-singular conic is isomorphic to $\mathbb{P}^1$. The underlying topological space is just a 2-sphere.