I know how to define a number field in sage by an irreducible polynomial over Q, for example
sage: K.<a> = NumberField(x^3 - 2)
sage: a.minploy()
But how do I define any number field like Q(√d1,√d2) in sage, where d1 and d2 are two distinct squarefree integers? So how do I find the defining minimal polynomial of the field extension Q(√d1,√d2) over Q?