Date: 10/27/96 at 19:24:46 From: Kimberly Subject: Geometry Exactly what are vertical angles? Thanks, Kimberly
Date: 10/28/96 at 12:14:43 From: Doctor Mike Subject: Re: Geometry Hi Kimberly, Vertical angles are like a pair of scissors -- you can't have just one scissor, and you can't have just one vertical angle. If you draw two straight lines that intersect then 4 angles are formed. Example: \ \ \ \ A _____________________\_______________________ \ A \ \ \ The pair of angles marked "A" are vertical angles. The other 2 angles are also a pair of vertical angles. You probably have heard the theorem that "vertical angles are equal". That is what lets me label those two angles with the same letter name "A". If one is 123 degrees, then so is the other. Vertical angles are like a pair of scissors in another way. If you open the scissors and lay them on a table, it looks sort of like two lines intersecting at the point where the two parts of the scissors are attached. I'm not sure why the word "vertical" is used for such angles. It probably does not have anything to do with vertical in the sense of straight up and down. Since the point where the lines meet can be called a vertex, the word vertical could be used to mean opposite angles that meet at the vertex. Are you interested in foreign languages? Lots of mathematicians are. That is because mathematicians from foreign countries write interesting mathematical books and magazine articles in their own language. In order to read that stuff before it gets translated, you have to know something about the other languages. I happen to know a little German so I looked up some geometry words in that language. "Winkel" is angle. "Punkt" is point. "Scheitelpunkt" is the point where lines cross over. "Scheitelwinkel" means vertical angle. "Scheitel" by itself means the top or summit, like of a mountain. If you look at the outline of a mountain from far away it looks like two lines meeting at the top. I hope this helps. If you get in a jam again, write us again. -Doctor Mike, The Math Forum Check out our web site! http://mathforum.org/dr.math/
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