Let \(X=S^n \backslash \{(0,\ldots ,1)\} \subseteq \mathbb{R^{n+1}}\) and \(Y= \mathbb{R^n}\) , and define
\(f:X \rightarrow Y\) and \(g:Y \rightarrow X\) by
\(f(x_1, \ldots ,x_{n+1}) =\large( \frac{x_1}{1-x_{n+1}}, \ldots , \frac{x_n}{1-x_{n+1}}),\\g(x_1, \ldots ,x_n)=\large(\frac{2x_1}{{||x||_2}^2+1} ,\ldots ,\frac{2x_n}{{||x||_2}^2+1} , \frac{{||x||_2}^2-1}{{||x||_2}^2+1} )\)
Verify that \(f\) and \(g\) are homeomorphisms such that \(f^{-1}=g\).
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