Recent content by Joffe

  1. J

    Trigonometry problem

    I have reduced a problem I am trying to solve to something simpler though rather difficult: Four side lengths and an angle uniquely describe a quadrilateral, solve one of the angles adjacent to the one given. No matter what algebraic / trigonometric manipulations I apply I cannot get a...
  2. J

    Probability Question

    'A' could be with any of the other 15 letters, so the chances of it being with B are 1/15, for that to happen n times is (1/15)^n EDIT: And for all the groups being the same it is not 1/120, it is \frac{2^8.8!}{16!} = 1/2027025
  3. J

    Infinite probability

    No, the first person's guess is irrelevant. No matter what he chooses the second person has a 1/10000 chance of matching it. What you described is the chances that they both pick the number 1 but what you are forgetting is that they could have both gotten 2 or 3 or any other number so you must...
  4. J

    Bad Math Jokes [Broken]
  5. J

    Line intersections.

    Thanks vsage. The speed is a huge factor, I will be having shapes of all kinds with no limit to the number of vertices, no convex constraints, and it will be possible to have shapes cut out of them [see these examples]. At the moment I was thinking this: 1. For each polygon edge: 2. If the...
  6. J

    Line intersections.

    I have a series of points on a 2 dimensional plane that form a polygon. Somewhere inside the polygon I have another point and an angle that defines a ray. What algorithm would I use to find which interval is first interstected with the ray? If the point happens to be outside the polygon then I...
  7. J

    Bad Math Jokes

    The guy who asked the question differs from the other because he was not involved in the selection. Imagine it this way, there are a thousand people and all but one are guilty, I could ask the guard which 998 of the others are guilty and it would narrow it down to me and one other guy, obviously...
  8. J

    Bad Math Jokes

    Actually posting that just compounds your stupidity (joking). For anybody who cannot see, the main man still has a 1/3 chance of survival, the known guilty guy has a 0 chance and the other a 2/3 chance. It has already been explained so I won't bother.
  9. J

    Challenge Challenge where you have to make each number from four 4s

    There is only one problem with that, there is an implied 10. I would definantly accept log in base 4 and maby the natural logarithm of an expression but that (albeit quite novel) just seems to violate in my opinion. If I don't ever find a better solution I think I will settle for that though...
  10. J

    Challenge Challenge where you have to make each number from four 4s

    Indeed, here are two more: 89 = (4-.4-4%)/4% 91 = (4-.4+4%)/4% 93 is all that remains!
  11. J

    Bad Math Jokes

    Thats an interesting puzzle Galileo, had me confused for a moment.
  12. J

    Why is zero factorial equal to 1?

    (n+\tfrac{1}{2})! = \sqrt{\pi} \prod_{k=0}^{n}\frac{2k+1}{2} I know that the gamma function can be used to solve factorials for any number but are there any other special rules like this one?
  13. J

    Power series

    No I don't, please enlighten me.
  14. J

    Who discovered Trigonometry?

    I have read that astronomers are responsible for much of the advances in trig hundreds of years ago but never seem to find who exactly pioneered this field of research.