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<C > \pi/2 id <A,<B,<C,<D,<E from an increasinf sequence in cyclic ABCDE

Source: 1996 Swedish Mathematical Competition p4

April 2, 2021
pentagonIncreasinganglesCyclicgeometry

Problem Statement

The angles at A,B,C,D,EA,B,C,D,E of a pentagon ABCDEABCDE inscribed in a circle form an increasing sequence. Show that the angle at CC is greater than π/2\pi/2, and that this lower bound cannot be improved.
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