We derive from this, one who made Havdoloh in prayer, is required to make Havdoloh on a cup - שמע מינה המבדיל בתפלה צריך שיבדיל על הכוס
Summary:
There are contradictory ברייתות whether one has to be מבדיל על הכוס, if he was מבדיל בתפלה. We assume that statements are made based on the custom of the majority.
And we can derive from this; the cup of blessing requires an amount - ושמע מינה כוס של ברכה צריך שיעור
Summary:
It is hard to say (in our ברייתא) that he only has one cup; the fact that he was not advised to divide the wine into two cups, proves that כוס של ברכה צריך שיעור.
We derive from this; he tasted it, he spoiled it - שמע מינה טעמו פגמו
Summary:
Initially we assumed that אין לו אלא כוס אחד means that (nevertheless) there was more than a רביעית. When drinking a כוס של חובה one must drink from a כוס which contains a רביעית of wine.