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the straight line KC is equal to CL, and the angle FKC to the angle FLC.
And, since KC is equal to CL, therefore
KL is double of KC.
For the same reason it can be proved that
HK is also double of BK.
And
BK is equal to KC;
therefore
HK is also equal to KL.
Similarly
each of the straight lines HG, GM, ML can also be proved equal to each of the straight lines HK, KL;
therefore
the pentagon GHKLM is equilateral.
