H
E
E
L
E
M
E
N
T
S
GA has the same ratio to each of the straight lines AK, AE.
Therefore
AE is equal to AK [V.9],
the less to the greater: which is impossible.
Therefore
ABCD cannot but be about the same diameter with AF;
Therefore
the parallelogram ABCD is about the same diameter with the parallelogram AF.
