With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: Eclipsing variables are star systems that vary in brightness because of one star passing in front of the other rather than from any intrinsic change in luminosity. W Ursae Minoris is one such system, its magnitude ranging from 8.51 to 9.59 over 1.7 days. The combined spectrum of the system is A2V, but the mass of one component star is known, though the other is unknown. A slight change in the orbital period in 1973 suggests there is a third component of the multiple star system—most likely a red dwarf—with an orbital period of 62.2±3.9 years. RU Ursae Minoris is another example, ranging from 10 to 10.66 over 0.52 ;days. It is a semidetached system, as the secondary star is filling its Roche lobe and transferring matter to the primary.
text_B: If one wanted to calculate a property of at least one of the component stars that required knowing the mass, could one do that?
YES.