Axes of SymmetryDate: 2/3/96 at 0:13:8 From: Anonymous Subject: Axes of symmetry Can you give me guidance on how to explain axes of symmetry to a year 5? My son had some trouble with it and I'm not sure as a parent how to explain in an intuitive way. Also, the correct answer to one question puzzled me a bit: a triangle was said to have three axes of symmetry, but it seems to me that this is only true for an equilateral triangle. By the way, my basic definition of an axis of symmetry is that it joins points on the perimeter in such a way that it divides the figure into two identical figures. I've checked the archives but couldn't find anything that seemed right for the level. Thanks for any help you can give. John Hannoush Date: 10/1/96 From: Doctor Ceeks Subject: Re: Axes of symmetry Hi, Symmetry is a very broad concept. I might try to explain it like this. Suppose you have an object, like a triangle. Suppose you're with a friend, and the friend leaves the room for the moment. While your friend is gone, you do something to the object... you move it, flip it, spin it, or something, in such a way that when your friend comes back, your friend can't tell the difference and has no idea you did something to the object. Then you've discovered a symmetry of the object. Now, if you rotated the object about an axis (like the earth spins on an axis), then there's an "axis of symmetry." For an equilateral triangle, there are four axes of symmetry, three in the plane of the triangle, and one that is perpendicular to the plane through the center of the triangle (120- or 240-degree rotation). -Doctor Ceeks, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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