Respuesta :

Hippalectryon
Let P be the last point in the triangle you have drawn from AB.. It is isosceles and rectangle hence AB^2=2BP^2 hence AP=BP=sqrt(2).

Let Q be the last point in the triangle you have drawn from CD. By the same reasoning, CQ=DQ=sqrt(2)

What is more, AD=AP+PQ+QD=2sqrt(2)+1