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Re: Beginner Question

• To: mathgroup at smc.vnet.net
• Subject: [mg66583] Re: Beginner Question
• From: "J Siehler" <jsiehler at gmail.com>
• Date: Sun, 21 May 2006 00:29:19 -0400 (EDT)
• References: <e4mmb8$6iu$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Sign[Det[{c - a, b - a}]]

will return +1 or -1 according as C on the right or left of the ray
from A to B.  (And 0 if C is colinear with A and B).