T H E E L E M E N T S	Book III   Proposition 29
	Now, since     the circumference BGC is equal to the circumference EHF,     the angle BKC is also equal to the angle ELF. [III.27] And, since the circles ABC, DEF are equal, the radii are also equal; therefore     the two sides BK, KC are equal to the two sides EL, LF; and they contain equal angles; therefore     the base BC is equal to the base EF. [I.4] Being what it was required to prove.
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