Re:Surprising Uses of the Pythagorean Theorem
by mrtron on Thursday October 25, 2007 @10:59AM
(#72517)
I really like the concept surrounding sorting.
It really helps you visualize why you need to separate your lists into smaller piles before sorting if you can, since it takes the same amount of time to sort a 50 element list as it does sorting a 40 and a 30 both.
Re:Surprising Uses of the Pythagorean Theorem
by pixcavator on Thursday October 25, 2007 @09:18AM
(#72474)
"Throughout our school life we think the Pythagorean Theorem is about triangles and geometry." Some of us still do. What he is talking about is Pythagorean triples. Well, maybe. Energy, for example, does not have to be an integer, so it's not really about Pythagorean triples. What is the point?
Re:Surprising Uses of the Pythagorean Theorem
by pixcavator on Thursday October 25, 2007 @03:07PM
(#72619)
Fair enough. Still, what is the point of the article? Some additive quantities are squares of other quantities, you add them, and it looks like the Pythagorean Theorem, without triangles... Is that it?
Re:Surprising Uses of the Pythagorean Theorem
by kalid on Thursday October 25, 2007 @04:25PM
(#72649)
Two main points, mostly to look at this old theorem in new ways.
1) The sides of a triangle (3-4-5) can represent portions of any shape. For example, circle area (radius 3) + circle area (radius 4) = circle area (radius 5).
Instead of radius, you could pick diameter, circumference, or any line segment and the relationship would hold.
2) You can use the Pythagorean Theorem to split any squared quantity into two smaller ones. This can yield surprising insights; is it immediately clear that a list of 50 takes as long to bubble sort as a list of 30 and 40? =)
Re:Surprising Uses of the Pythagorean Theorem
by pixcavator on Thursday October 25, 2007 @06:30PM
(#72702)
There may be a point here, but I am still uncomfortable with the use of the Pythagorean theorem here. Even if applied to areas only, it seems like a stretch. In fact with this approach one can suggest other identities. For example, if you replace squares with cubes (or circles with spheres), you will have a^3+b^3=c^3. And this clearly has nothing to do with the Pythagorean theorem.
It really helps you visualize why you need to separate your lists into smaller piles before sorting if you can, since it takes the same amount of time to sort a 50 element list as it does sorting a 40 and a 30 both.
50^2 = 25^2 + 43.3^2
Strictly speaking, if you have a circle of radius 50, you can take the sine and cosine of any angle and get a possible way to split the length.
1) The sides of a triangle (3-4-5) can represent portions of any shape. For example, circle area (radius 3) + circle area (radius 4) = circle area (radius 5).
Instead of radius, you could pick diameter, circumference, or any line segment and the relationship would hold.
2) You can use the Pythagorean Theorem to split any squared quantity into two smaller ones. This can yield surprising insights; is it immediately clear that a list of 50 takes as long to bubble sort as a list of 30 and 40? =)