The values of sin2alpha and sin2beta, where alpha and beta are angles of the unitarity triangle, will be readily measured in a B factory (and maybe also in hadron colliders). We study the standard model constraints in the sin2alpha-sin2beta plane. We use the results from recent analyses of f(B) and tau(b) \V(cb)\2 which take into account heavy-quark symmetry considerations. We find sin2beta greater-than-or-equal-to 0.15 and most likely sin2beta greater-than-or-similar-to 0.6, and emphasize the strong correlations between sin2alpha and sin2beta. Various schemes for quark mass matrices allow much smaller areas in the sin2alpha-sin2beta plane. We study the schemes of Fritzsch, of Dimopoulos, Hall, and Raby, and of Giudice, as well as the ''symmetric Cabibbo-Kobayashi-Maskawa'' idea, and show how CP asymmetries in B decays will crucially test each of these schemes.