Poncelet's theorem states, that if $n$-sided polygon is inscribed in conic $S_1$ and circumscribed about conic $S_2$, then there exists infinitely many of such polygons. Moreover, for any point $P$ of $S_1$, there exists an $n$-sided polygon, also inscribed in conic $S_1$ and circumscribed about conic $S_2$, which has $P$ as one of its vertices, and for any point $R$ of $S_2$, there exists an $n$-sided polygon, also inscribed in conic $S_1$ and circumscribed about conic $S_2$, such that tangent to $S_2$ from $R$ is one of its lines. In real projective plane we first explain special case of Poncelet's theorem for triangles and then the general case. For that we use Pascal's theorem, Brianchon's theorem, Carnot's theorem, dual of Carnot's theorem and some other claims.
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