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For, since
the angle FKC is equal to the angle FLC,
and
the angle HKL was proved double of the angle FKC,
and
the angle KLM double of the angle FLC,
therefore
the angle HKL is also equal to the angle KLM.
Similarly
each of the angles KHG, HGM, GML can also be proved equal to each of the angles HKL, KLM;
therefore
the five angles GHK, HKL, KLM, LMG, MGH are equal to one another.
