3 d : d
aa + bb : aa - bb ∷ cc + dd : cc - dd
mab : 2aa + bb ∷ mcd : 2cc + dd
If the two means of a proportion be the same, that is, if a b ∷ b : c , the three numbers, a , b , and c , are said to be in continued proportion, or in geometrical progression . The same terms are applied to a series of numbers, of which any three that follow