Definition talk:Triangle (Geometry)

Quick question to clear up confusion: does it make sense to say "three vertices and three angles"? Either one or the other ought to do. The way I've defined vertex I've made it so that the "vertex" is the thing and the "angle" is the measure of the thing.

Perhaps worth while pointing out that "informally" the word "angle" is often used for "vertex", although "strictly speaking" the angle is the measure of the vertex? What say? --Matt Westwood 15:04, 1 January 2009 (UTC)

Actually, I think you need to specify both angles and vertices. For example, imagine an hourglass: it would have 5 vertices (2 top, 1 middle, 2 bottom) but 6 angles (2 top, 2 at the middle intersection, 2 bottom). --Cynic-----(talk) 02:25, 4 January 2009 (UTC)

Good point ... but now you mention that, we need to extend the definition of polygon to differentiate between a "simple polygon" (like what's already been defined) and a self-intersecting one. A simple polygon has as many vertices as angles and therefore the aforementioned definition applies. --Matt Westwood 07:28, 4 January 2009 (UTC)