Van Roomen's problem

The development of a famous polynomial p(x) of degree 45 has already been discussed here. Now I searched further and found Vieta's approach to the ingenious determination of the zeros. His approach, identical to p(x), is p(x) = 2*sin(45*arcsin(x/2)). Mathcad 14 fully develops this. But I fail to get the usual polynomial structure to be able to compare it with the classical default. What am I doing wrong in attached file? Kind regards at Christmas time, Alfred Flasshaar