Math

Finding the Common Intersection of Three Planes Each Found by a Fit Using LSQ
try a search on Gauss & Ceres. or "go" to wlym.com. This problem and its solution are found in a paper by Ceplecha,  1987, but the details are murky to me. For two, I'm pretty much OK, but for three and above it escapes me. His paper covers a lot more territory than this problem, but this one is what int... 8 May 2010 16:43

Triangulation, Multiple Observers
Google doesn't seem to help on Subject. What math method would solve a triangulation of a point by two, three, or more observers of a point? Assume the observers are on a plane, work from a common x-y coordinate system, and make some error in their angular measurement. Would the same method be used if each obse... 9 May 2010 08:54

Did Archimedes could knew this?
Lim (Arc - cord) = (Tangent - arc) / 2 Because in that case he could have improved the calcul of Pi through: Lim Arc = (2*cord + tangent) / 3 As he stablished that 3 + 10 / 71 < pi < 3 + 1 / 7 he could have taken C = (20 / 71 + 1 / 7) / 3 and then: pi aprox. = 3 + C = 3.141515... Ludovicus ... 10 May 2010 21:02

Differentiation of exponential functions.
Let f(x) = (x ^ 2) * e ^ x . Find {x: f'(x) < 0} f'(x) = (x ^ 3) * e ^ x. Solve (x ^ 3) * e ^ x = 0 x = 0 f'(-1) = -e ^ -1 = -1 / e f'(1) = e Sign diagram indicates gradient is negative when x < 0. Now I graphed f(x) on my calculator; it's clea... 8 May 2010 13:25

Borel sets of the extended real line
hi, see here: http://mathoverflow.net/questions/23826/what-is-the-associated-borel-set-of-a-borel-measurable-function-on-the-extended-r ... 8 May 2010 09:01

convex hexagon problem (area of cut-off triangle) ? (Engel)
This is a problem from Engel's book 'Problem Solving Strategies', chap 4, prob 22. Show that in any convex hexagon, there is a diagonal which cuts off a triangle with area <= (1/6)* area of hexagon. I've done the first part. Engel says the second part is easier, but I'm stuck on it! OK take the case where t... 9 May 2010 09:58

NEW CHRISTMAS IS BY BATCH, MIGHT START THIS YEAR
1. It is very clear now that Christmas is by batch, and even Bolkiah will be replaced soon, unless… The pace is disco pop now, thanks to God’s timely intervention, not the anemic beat of Bolkiah and Buckingham with just too-toot-toot, no dynamics, movement and all. There is a break between Christmas generations,... 8 May 2010 02:35

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
www.James-Randi.com ... 7 May 2010 23:21

To PI or not to PI challenge. Stern-Brocot
The answer to the famous Shakespeare's question seems to be: Not to PI, just close... It seems that the new record is for Xitrami at the Physicsforums: 3.13288 http://physicsforums.com/showthread.php?p=2707370&posted=1#post2707370 Let's see what others have to say about such value. ... 7 May 2010 23:21

Taking Great Pride In Low Tech Long Overlooked Inventions
Am I the only one? Bret Cahill ... 8 May 2010 01:31