# The Grey Labyrinth is a collection of puzzles, riddles, mind games, paradoxes and other intellectually challenging diversions. Related topics: puzzle games, logic puzzles, lateral thinking puzzles, philosophy, mind benders, brain teasers, word problems, conundrums, 3d puzzles, spatial reasoning, intelligence tests, mathematical diversions, paradoxes, physics problems, reasoning, math, science.

Author Message
CzarJ
Hot babe

 Posted: Wed Mar 01, 2000 1:14 am    Post subject: 1 Perhaps it would be best if we had a place where we could put all the formulas we can think of (whoa, long list). I'll start: GEOMETRIC AND FERMAT'S LAST THEOREM code:``` square: A=L^2 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ rectangle: A=LW (perimeter: P=2L+2W) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ circle: A=pi*r^2 (circumference: C=pi*d) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ triangle: A=(1/2)*b*h ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ trapezoid: (1/2)*h(b1+b2) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ surface area of sphere: S=4*pi*r^2 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ volume of sphere: (4/3)*pi*r^3 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ cube:V=s^3 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ rectangular prism: V=LWH ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ cylinder: V=pi*h*r^2 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ pyramid: (1/3)bh ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Pythagorean Theorem: a^2+b^2=c^2 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Fermat's Last Theorem: x^3+y^3=z^3 ``` Ok,ok, I have no idea what that last one is, and it probably has nothing to do with area. Algebraic code:``` Slope Formula: m=(y2-y1)/(x2-x1),where m is the slope and (x1,y1) and (x2,y2) are coordinates for 2 points on a plane. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Quadratic Formula: if ax^2+bx+c=0,x=(-bħsqrt(b^2-4ac))/2a ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Distance between two points: d=sqrt((x2-x1)^2+(y2-y1)^2), where (x1,y1) and (x2,y2) are coordinates for 2 points on a plane. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Midpoint Formula: The midpoint between (x1,y1) and (x2,y2) is (((x1+x2)/2),((y1+y2)/2)) ``` PROBABILITY code:``` The probability of any given outcome in 2 related events is P(x)*P(y) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Binomial(n,k)=(n!)/(k!*(n-k)!) ``` Please tell me where I screwed up and feel free to add others. [This message has been edited by CzarJ (edited 05-22-2001).]
AcidFast
Daedalian Member

 Posted: Wed Mar 01, 2000 2:49 am    Post subject: 2 If you would like to know more about Fermat's Last Theorem (or FLT for short...), you can check it out [url=http://www-groups.dcs.st-and.ac.uk/~history/HistTopics/Fermat's_last_theorem.html]here[/url]. Its actually a very interesting little story. [This message has been edited by AcidFast (edited 02-29-2000).]
Amy
Daedalian Member

 Posted: Thu Mar 02, 2000 3:32 pm    Post subject: 3 For even more wild fun, we should try deriving these ourselves.
araya
Daedalian Member

 Posted: Fri Mar 03, 2000 2:47 am    Post subject: 4 I was waiting for somebody else to notice, but that pyramid equation is a bit fishy
Ghost Post
Icarian Member

 Posted: Fri Mar 03, 2000 9:01 pm    Post subject: 5 I think the pyramid formula is right. V = 1/3 * B * h, where B= Area of the base. I believe this is true regardless of the shape of the base. So, a cone's volume is: V = 1/3 * (Pi * r^2) * h If the base is a square, you'll get: V = 1/3 * (s^2) * h Somebody correct me if I'm mistaken.
araya
Daedalian Member

 Posted: Sat Mar 04, 2000 2:54 am    Post subject: 6 oh yeah, that is right.. looking at the equation, it looked like an area equation (dimensional analysis). It wasn't clear that b was an area measure.
CzarJ
Hot babe

 Posted: Sat Mar 04, 2000 11:42 pm    Post subject: 7 A few corrections: Fermat's last theorem: x^n+y^n=z^n The name of this thread should be "Formulae" and an addition: Falling Object Model: h=-16t^2+s, where h is the height at time t when dropped from original height s.
araya
Daedalian Member

 Posted: Sun Mar 05, 2000 1:37 am    Post subject: 8 Fermat's last theorem is that there are no integer solutions for x^n + y^n = z^n for n > 2. What are the units on your falling object equation?
CrystyB
Misunderstood Guy

 Posted: Sun Mar 05, 2000 12:07 pm    Post subject: 9 for the falling object: PLEASE say in what units you measure the acceleration. I am used to 9.80665 m/(s^2), so we would have h=s-5(t^2). And you have been in a little hurry when typuing the distance between two points and forgot the second "square" (or at least its exponent). What about TRIG? Never heard of sin(sum)=sincos+sincos, cos(sum)=coscos-sinsin? And all the other hundreds of formulAE?
Quailman
His Postmajesty

 Posted: Sun Mar 05, 2000 8:55 pm    Post subject: 10 Objects fall at a different rate in the US than they do elsewhere. That's 32 feet per second^2.
CzarJ
Hot babe

 Posted: Tue Mar 07, 2000 7:29 pm    Post subject: 11 sorry about the falling object thing. I don't know anything about trig, so I'll have to rely on the rest of you to help me out there. This wasn't intended to be just me typing everything I could think of. h=-16t^2+s where h=height in feet at time t in seconds, dropped from an initial height (in feet) of s.
godeloo
Daedalian Member

 Posted: Sun Mar 12, 2000 5:39 pm    Post subject: 12 x^2+y^2=Z^2 This formula has an infinite number of whole number solutions. If you want some just ask
mithrandir
Daedalian Member

 Posted: Sun Mar 12, 2000 5:47 pm    Post subject: 13 that's why n > 2
CrystyB
Misunderstood Guy

 Posted: Thu Jun 08, 2000 8:05 pm    Post subject: 14 godeloo, please tell me some more pythagorean numbers besides the all-known n, (n^2-1)/2 and (n^2+1)/2, for any n which is an odd (i mean 2k+1, i never knew what odd/even are for) positive integer. P.S. CJ, i usually don't like repeating myself, but you might not have heard: you're missing a "^2" in the distance formula. And the last two of "Area & Volume" should be in "Theoremes" or something. edited on 06-08, 06-20 and: [This message has been edited by CrystyB (edited 08-14-2000).]
mathgrant
A very tilted cell member

 Posted: Tue May 22, 2001 7:42 pm    Post subject: 15 Bump. ------------------ "Mathematics is like the Nile, begins in minuteness, ends in magnificence." --Charles Caleb Colton
Ghost Post
Icarian Member

 Posted: Fri May 25, 2001 3:31 am    Post subject: 16 Do you want to keep this isolated to math and calc formulas (abstract stuff), or should I dig up all my (concrete) physics formulas too?
CzarJ
Hot babe

 Posted: Fri May 25, 2001 4:19 pm    Post subject: 17 Have at it! ------------------ Basket-Weaving For Donuts, Where You Weave Baskets And Get Donuts.
mole
Subterranean Member

 Posted: Fri May 25, 2001 9:57 pm    Post subject: 18 The probability of a given outcome in two related events is (Depending on the events) P(x) * P(y|x) Not sure about the notation, but that's meant to say "the probability of y provided x happens" YOu shouldn't have to worry about it most of the time (flipping coins is a good example), but the extra factor is important when dealing cards, or other things that change the situation when the event occurs.
Ghost Post
Icarian Member

 Posted: Sat May 26, 2001 7:47 am    Post subject: 19 Well, I started typing out physics formulas, but I realized that a large portion of them either use special unicode characters only visible to users of windows 2000 (such as delta, gamma, and mu), or they use subscripts and superscripts which can't be expressed in UBB, or both. I decided instead to simply scan in my formula sheet . It is now posted at http://www.mnefstead.f2s.com/images/phys11.gif When I have my physics 12 formula sheet handy, I'll scan that too. Cheers! [This message has been edited by ThePoet (edited 05-26-2001).]
Ductape
Guest

 Posted: Fri Jun 01, 2001 2:40 am    Post subject: 20 Hero's formula A^2=(s(s-a)(s-b)(s-c)) s=1/2 (a+b+c) i think this is for area of a triangle
CrystyB
Misunderstood Guy

 Posted: Fri Jun 01, 2001 11:21 am    Post subject: 21 Why did you bumped it? There is the possibility of "Show all topics..." And btw, the distance between two points in space is sqrt((x1-y1)^2+(x2-y2)^2+(x3-y3)^2) [This message has been edited by CrystyB (edited 07-30-2001).]
mole
Subterranean Member

 Posted: Fri Jun 01, 2001 1:42 pm    Post subject: 22 Or should that be sqrt((x2-x1)^2+(y2-y2)^2+(z2-z1)^2)?
Ghost Post
Icarian Member

 Posted: Thu Jun 28, 2001 2:03 am    Post subject: 23 How about PV=nRT... etc etc etc... or does chemistry not count?
CrystyB
Misunderstood Guy

 Posted: Mon Jul 30, 2001 4:51 pm    Post subject: 24 I subsribe to PV=nRT !!! Please add a chemistry section... I LOVE chemistry. Ow, i mean i lovED chemistry. I can only think of concentration formulae right now: In a water-solution of a substance, the mass concentration is (100*m_subst/m_solution)% the volum(etr)ic concentration is (100*V_subst/V_solution)% the molar concentration is (m_subst/MM_subst)/V_solution[in liters] (MM means molecular mass) the normal concentration is molar_concentration/nb_electrons_"used" (eg: that number is 1 if HCl, 2 if Na2SO4, 3 if AlPO4 and so on) [This message has been edited by CrystyB (edited 07-30-2001).]
 Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year by All usersAcidFastAmyAnonymousarayaCrystyBCzarJGhost PostgodeloomathgrantmithrandirmoleQuailman Oldest FirstNewest First
 All times are GMT Page 1 of 1

 Jump to: Select a forum Puzzles and Games----------------Grey Labyrinth PuzzlesVisitor Submitted PuzzlesVisitor GamesMafia Games Miscellaneous----------------Off-TopicVisitor Submitted NewsScience, Art, and CulturePoll Tournaments Administration----------------Grey Labyrinth NewsFeature Requests / Site Problems
You cannot post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum