V.9 Proposition V.9
Magnitudes which have the same ratio to the same are equal to one another; and magnitudes to which the same has the same ratio are equal.
Proof
Contrapositive of V.8: if a=b, then a:c=b:c. Hence if
a:c=b:c then a=b. Same argument with c as antecedent.
lines 74–74 in main.tex