Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

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#151 Re: Maths Is Fun - Suggestions and Comments » Introduction to Logarithms » 2007-11-26 18:02:10

Awesome, very helpful beginners guide.

The only thing that bugs me are the lines: "Engineers love to use it." and "Mathematicians use this one a lot." Those lines just don't satisfy my inner "why?"

Might I suggest adding a "because..." to each sentence?

#152 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-26 16:49:15

25% = 1/4

100% = 1

100% + 25% = 1 + 1/4 = 4/4 + 1/4 = 5/4

You start with one x, then you add 25% of x to that, and that makes 125% of x.

#153 Re: Dark Discussions at Cafe Infinity » NFL football » 2007-11-26 10:37:05

I'm not a football fan, but I am from New Hampshire so I think I'm geographically motivated to be against you on this topic.

So, boo to your Eagles, go Pats!

#154 Re: Help Me ! » help me please » 2007-11-25 14:41:10

Oh, math, yeah... like I said, long day.

Thanks.

#155 Re: Help Me ! » help me please » 2007-11-25 13:10:31

It could be just that I had a long day at work but... really?

a/c - b/c = (a-b)/c

No? I don't doubt that I'm wrong here (like I said: long day) you do tend to be awesome at this kind of thing, but I'm not getting it.

(I feel like such a fool).

#157 Re: Help Me ! » help me please » 2007-11-25 12:39:12

I don't know, I think I just made it worse...

#160 Re: Help Me ! » What is a good topic for a statistical research? » 2007-11-18 03:49:34

How about polling a bunch of your classmates to find some cool fact like:

boys like video games more than girls.
older students hate school more.
Students who play sports get better grades.

I don't know if any of those above statements are true, but it would be kind of fun to find out (even if the info you find is only accurate for your region).

#161 Re: Help Me ! » Evaluate » 2007-11-15 06:41:52

The question could just as easily be evaluate sinx seeing how

cotx = sinx

multiply both sides sinx

cosx = sin²x

Using the trig identity sin²x + cos²x = 1 we get:

cosx = 1 - cos²x

u = cosx

u² + u - 1 = 0

u = (-1±√5)/2

cosx = (-1±√5)/2 = sin²x

sinx = cotx = √[(-1±√5)/2]

It's been a while since I had to do trig, did I make any mistakes?

#162 Dark Discussions at Cafe Infinity » Which book should I read first? » 2007-11-15 05:08:24

bossk171
Replies: 10

I have two books, both on subjects I'm fascinated by, both subjects way over my head.

The first is the four color theorem,  the second on Abel's proof that the quintic is unsolvable.

Which would be more approachable for someone who's education only includes High school up to and including Calculus? Which is more interesting to you guys? Which am I going to get halfway through, realize it's much harder than thought and give up in a fit of rage?

#163 Re: Help Me ! » integration » 2007-11-15 05:00:19

You know, I'm embarrassed to say I've never seen that "general rule" before. It makes sense though.

You really do learn something new every day.

#164 Re: Euler Avenue » Things they never teach you in algebra » 2007-11-07 15:44:15

This is great! Ricky (or anyone else) do you have any more "things they never teach you in algebra." I'm looking forward to learning new things like number theory and what not, but I love to expand on my pre-existing knowledge (like Algebra).

Everything TheDude said in his post could be followed by a good algebra II student, and that's what makes it genius, this stuff makes me all warm and fuzzy inside.

Also, TheDude, you have a really sweet sig.

#165 Re: This is Cool » hi i got bored so i did this » 2007-11-06 18:11:42

1+2+...+39+40 = 40(40+1)/2 = 820

23*72 = 1656

820+1656=2476

#166 Re: Coder's Corner » Intersecting line segments algorithm » 2007-11-05 10:39:06

I think it's the vector notation I'm getting hung up on. The explanation: "In otherwords, he is defining two infinite lines, finding where they intersect, and then seeing if the lines fall within the boundaries of the line segments." really helps though.

Thanks for really breaking it down for me guys, and especially thanks for posting that fla.

#167 Re: Help Me ! » Ramanujan » 2007-11-04 08:57:08

Where do we place the emphasis?

ra MAN u jan

or

RA man u jan

#168 Help Me ! » Ramanujan » 2007-11-04 07:37:04

bossk171
Replies: 7

Awesome Mathematician, One of my personal heroes. The only thing that's always gotten me: How do you pronounce it?

Can someone through out a phonetic spelling for me?

#169 Re: Dark Discussions at Cafe Infinity » how much you train? » 2007-11-04 03:07:08

I find that depending on the difficulty of the subject, my training varies. I can get a pretty good understanding of a subject by just listening, but to know it completely, I have to practice with it a bit.

#170 Re: Coder's Corner » Intersecting line segments algorithm » 2007-11-03 15:23:22

I really hate to say this but... what?

Am I missing something here? That still seems really confusing.

#171 Re: Maths Is Fun - Suggestions and Comments » Can this site be made Font Size Friendly? » 2007-11-03 03:40:06

I'm on laptop, but use firefox (which is far superior to IE) I've yet to have a problem.

#172 Coder's Corner » Intersecting line segments algorithm » 2007-11-02 14:45:28

bossk171
Replies: 5

I'm working on a Flash game, and I can't come up with a simple algorithm to test if to line segments intersect.

I know I can do it, but as I go along things get more and more complicated (which means: more room for bugs) and I keep thinking there's got to be and easier way of doing it.

So I googled it, and came across this essay on a "sweep line algorithm" but that seems even more complicated then the way I was doing it.

Is there an easier way to do it? I know Actionscript isn't a very popular programming language (unless you're into game design) so if someone can just give me the theory, or maybe an example in C++ (that's the only other language I know) I would really appreciate it.

I really feel like I'm missing something here, this should be real easy, and yet...

#173 Re: Dark Discussions at Cafe Infinity » I wrote this song this morning. » 2007-10-31 02:34:19

I've been using MODTRACK and I'm very happy with it.

I don't know much about music, but it's very user friendly.

#174 Re: Help Me ! » Symbols » 2007-10-31 02:29:39

Thanks everyone.

Ricky, your log explanation was particularly helpful, I guess it makes sense to just look at the context.

#175 Help Me ! » Symbols » 2007-10-30 03:42:53

bossk171
Replies: 6

My math background is High school Calculus, and everything that comes before it, and I love math. I've been hanging out on these boards for a while now and I have a question that's really been bothering me...

I'm really getting hung up on notation. Before being on these boards, I'd never seen "∴" used anywhere. By clicking on the Latex code I figured out it means "Therefore." But What is the difference between "∴" and "⇒" i.e. when do I use one and not the other?

What are some other notations? Is there a symbol for "if" I'm pretty sure the symbols for "and" and "or" are shapes something like"U"s.  What does " •" mean? Is there a difference between American notation and British notation? Australian Notation? Canadian Notation? For example, I was taught to use "ln" for natural log, but books I read by British authors use "log" (which I use for log base 10).

This is quite frustrating for me, and it must seem like a really dumb question to most of you, but can someone help me out with this? Or at least send me a half way decent link? Thanks.

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