T H E E L E M E N T S	Book IV   Proposition 7
	Now, since     the angle AEB is right, and     the angle EBG is also right, therefore     GH is parallel to AC. [I.28] For the same reason     AC is also parallel to FK, so that     GH is also parallel to FK. [I.30] Similarly we can prove that     each of the straight lines GF, HK is parallel to BED.
	Previous Page    Return to Propositions    Next Page