Faster Than Algebra
Date: 05/14/2002 at 10:30:59 From: Chris Floyd Subject: algebra My students are working on a competition problem and I can't for the life of me figure it out: "The sides of a rose garden in the shape of a right triangle are in a ratio of 8:15:17. If the perimeter is 60 feet, what is the length of the shortest side?
Date: 05/14/2002 at 12:51:59 From: Doctor Peterson Subject: Re: algebra Hi, Chris. If the sides were actually 8, 15, and 17, the perimeter would be 8+15+17 = 40. You want the perimeter to be 60/40 of that (that is, 3/2); so you just have to multiply each side by 3/2. The sides will be 12, 22.5, and 25.5 feet. But you only need to report the 12. This approach, taking the simplest guess and seeing what it takes to change the answer into what you want, is an ancient one and often faster than algebra! The equivalent, using algebra, is to call the sides 8x, 15x, and 17x, and write an equation for the perimeter. - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/
Date: 05/15/2002 at 09:49:47 From: Chris Floyd Subject: algebra Question submitted via WWW: Thank you so much for your help with what seemed like a trivial problem; I just couldn't visualize it. I appreciate your time.
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