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S		 Book VI   Proposition 6
Let ABC, DEF be two triangles
    having one angle BAC equal to one angle DEF
and the sides about the equal angles proportional, so that
    as BA is to AC,
    so is ED to DF;

I say that
    the triangle ABC is equiangular with the triangle DEF;
and will have
    the angle ABC equal to the angle DEF,
and
    the angle ACB to the angle DFE.
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