I was going through the section "Heron's proof of AL,BK.CF in Euclid's Figure meet in a point", in God Created the Integer's book . The statement of problem and its proof are both in very vague form. While searching the internet, all I found was link to the "The Thirteen Books Of Euclid", which also has exact same vague statement and proof. It seems Hawkins lifted it straight from that book. Any how, I want to know the exact problem statement and proof.