Secant line a circle in the Euclidean plane, a line joining two of them would be a 2-secant (or "bisecant") and a line passing through only one of them would be a 1-secant (or "unisecant"). A unisecant in this example need not be a tangent line to the circle. This terminology is often used in incidence geometry and discrete geometry. For instance, the Sylvester–Gallai theorem of incidence geometry states that if points of Euclidean geometry are not collinear then there must exist a 2-secant of them. And the original orchard-planting problem of discrete geometry asks for a bound on the number of
A-not-A question an echo answer, stating either "I am happy," or the correct alternative, "I am sad". In other words, this sentence is a leading question, where the speaker has an expectation as to what the answer will be. In contrast, (1.b) "Are you happy or not?" is a neutral question where the answer to this can be yes or no in response to the first and more explicitly stated alternative. A-not-A questions are not usually used in English, but the following example shows how A-not-A questions are answered. As seen in this example, simply answering "Yes" or "No" does not suffice