Normal (geometry) Normal (geometry) In geometry, a normal is an object such as a line or vector that is perpendicular to a given object. For example, in two dimensions, the normal line to a curve at a given point is the line perpendicular to the tangent line to the curve at the point. In three dimensions, a surface normal, or simply normal, to a surface at a point "P" is a vector that is perpendicular to the tangent plane to that surface at "P". The word "normal" is also used as an adjective: a line normal to a plane, the normal component
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