Question

The third proportion between A square-B square and( A+B) square

Answer 1

We know that  a/b = b/c

  or third proportion c = b^2 / a

 Given a = a^2 - b^2

            b = (a + b)^2

 Substituting  c = ( (a + b)^2)^2 / a ^2 - b^2

             c = (a + b)^2 x (a + b)^2 / (a + b)(a - b)

           c = (a + b)^3/ (a - b)