Geometry: Proofs About Quadrilaterals

Proofs About Quadrilaterals

When the game Twenty Questions is played, one person thinks of an object, and the other people can ask “yes/no” questions to try and figure out what the object is. This game helps pass the time when traveling on long trips. On your next trip, if you find yourself bored with twenty questions and the license plate game, you might want to play a new game.

Now that you have our quadrilaterals in a row, it's time to learn how to pick them out of a line-up. In Putting Quadrilaterals in the Forefront you learned about the various properties of special quadrilaterals. You'll put that information to use by playing “Name That Quadrilateral.” Here are the rules: I'll give you some clues about a quadrilateral, and you identify its type.

For example, I'm thinking of a parallelogram that has congruent and perpendicular diagonals. Name that parallelogram. To name that parallelogram, go down your list. Rectangles have congruent diagonals, but they aren't perpendicular. Rhombuses have perpendicular diagonals, but they aren't congruent. Squares, being a hybrid of rectangles and rhombuses, have congruent diagonals and perpendicular diagonals. We have a winner!

Excerpted from The Complete Idiot's Guide to Geometry © 2004 by Denise Szecsei, Ph.D.. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.

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