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### Alternate Exterior Angles

```Date: 06/03/2002 at 15:45:58
From: S.B.
Subject: Geometry definitions

Dear Dr. Math

I have been trying to find out what exterior alternate angles are
for hours! My teacher assigned us a vocabulary sheet for geometry, and
the only term I can't find is alternate exterior angles. I know what
an alternate interior angle is, but not an exterior one. I am

Thanks------ S.B.
```

```
Date: 06/03/2002 at 17:08:38
From: Doctor Peterson
Subject: Re: Geometry definitions

Hi, S.B.

Here's a clue, from everyday English usage: "interior" means
"inside", and "exterior" means "outside". (You may see those words on
paint can labels, for example.)

So alternate _interior_ angles are on opposite sides of the
transversal, _between_ the parallel lines, like the pair of x's and
the pair of y's here:

\
---+-------
x \y
\
y\ x
-------+---
\

Alternate _exterior_ angles are also on opposite sides of the
transversal, but _outside_ the parallel lines:

x\ y
---+-------
\
\
\
-------+---
y \x

I suspect a lot of students hear these phrases as a whole, and never
stop to think what the individual parts (alternate, interior,
exterior) mean -- because they expect math terms to be
incomprehensible and unrelated to real life! Sometimes math makes
more sense than you realize at first.

Maybe I can also help you not have to look for hours next time. To
find what a word means, I would first go to a regular English
dictionary; then maybe try one of the dictionary or encyclopedia
resources listed in our FAQ, or search our site; then go to
google.com and enter the phrase "alternate exterior angles" to see if
there is a definition on the web. You'll find it!

- Doctor Peterson, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics:
High School Definitions
High School Euclidean/Plane Geometry
Middle School Definitions
Middle School Two-Dimensional Geometry

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