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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#3376 Re: Puzzles and Games » Secret message » 2005-12-23 15:15:51

Your on the right track!  Nice work krassi_holmz.

#3377 Re: Maths Is Fun - Suggestions and Comments » Can we reach for the stars? » 2005-12-22 14:44:37

I made one.  You can find it by searching on "Braille".
The carriage returns didn't get saved though, so you
can't read the Braille message.

#3379 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-12-22 14:16:24

ganesh, do you have a list of the problems
that are unsolved?  That way I can go back
easier and solve some old ones.

#3381 Re: Help Me ! » Venn Diagrams » 2005-12-22 13:59:57

Click on image to enlarge.
Note colored numbers.
That may help you.
Work from the center to the flower petals, and then
to the biggest parts.
The top line is boys, the bottom line is girls.

#3382 Dark Discussions at Cafe Infinity » This is definately cruelty to animals. » 2005-12-22 11:06:20

John E. Franklin
Replies: 1

I am really horified by this treatment of animals.

mms://a805.v9135e.c9135.g.vm.akamaistream.net/7/805/9135/0029/peta.download.akamai.com/9135/downloads/jcruel_china_dog_med.wmv

#3383 Re: Dark Discussions at Cafe Infinity » Cow Bull 1 » 2005-12-22 10:22:26

I bet it is cause I almost guessed that, I was gonna choose between
either 6 or 9, but I chose 6.

#3384 Re: Introductions » Winter Lover » 2005-12-22 10:20:05

Happy Winter!!!!!
Boy am I happy now!!
I love the wintertime...

#3385 Re: This is Cool » polygon area » 2005-12-22 08:24:50

I went there and I found this:
Even Tandog has a trick formula for polygon areas. There's also an extract from Shakespeare's long forgotten play Henry X11 part 5 and finally... the secret identites of the superheros are revealed.

#3386 Re: Help Me ! » Is there any way to solve this algebraically? » 2005-12-22 08:13:55

at the end of post#5 I had  x-1 = x/2, but is this allowed since
I took the inverse of the functions?

#3387 Puzzles and Games » Secret message » 2005-12-22 07:34:09

John E. Franklin
Replies: 8

Graph the twelve equations
on top of each other for a message.
1. y= (3/2)x+1;


2. y= (-3/2)(x-2)+1;

3. y= 9(x-3)+4;

4. y= -9(x-5)+4;

5. y= -(x-4)+3;

6. y= (x-4)+3;

7. y= 2;  19/3 < x < 23/3
8. y= 3(x-6)+1;

9. y= -3(x-8)+1;

10. y= (1/2)(x-9)+1;

11. y= (-1/2)(x-10)+5/2;

12. y= (1/2)(x-11)+4;

#3388 Dark Discussions at Cafe Infinity » Rubic's Cube solution » 2005-12-21 11:51:47

John E. Franklin
Replies: 30

Does anyone know who came up with
the various solutions of the Rubik's
cube and how they went about
finding the moves that rotate the
corners without much disturbance
of rest of cube, etc?

#3390 Re: This is Cool » polygon area » 2005-12-21 11:18:50

I would be interested in finding info on that formula.
Do you know of any links.
I'll check around first...
...I found it at one web page, but no explanation...
This looks even more general!!

#3391 Re: Help Me ! » Finding an inverse function » 2005-12-21 11:13:40

x and y are variables, so I don't think you can set y equal to a.
How can you do that?

#3392 Re: Help Me ! » Is there any way to solve this algebraically? » 2005-12-21 11:02:50

What about the inverses of the functions?



I don't know what to do next.

If you combine mathsypersons stuff with mine,
you get x-1 = x/2, but I don't know if that's legal
after I took the inverse.

#3393 This is Cool » polygon area » 2005-12-21 10:33:36

John E. Franklin
Replies: 8

Perhaps this result is true.
I just worked it out with my
silly new calculus of a hexagon.(this thread)
This result is for any regular
polygon (all sides equal and all angles equal).

It works for a square of length 5.
And for a pentagon of side length 5, it says 43.01, but I don't know if it is right.

#3394 This is Cool » hexagon area with calculus » 2005-12-21 05:16:48

John E. Franklin
Replies: 3

Make sure you integrate perpendicular to the  side of the polygon.
I mean the x-axis cuts a side of the polygon in half.
The 12 in the following equation is the perimeter.

The reason for the :sqrt 3 in the denominator is because all of the
thousands of hexagons inside one another are similar or proportional.
So you can look at the biggest one, and when x is :sqrt 3, then
you want 12dx for that skinny donut area.

The thing that interests me is what happens at all the vertices?
It is surprising it works.

#3395 Re: Maths Teaching Resources » Calculus in the suspension bridge » 2005-12-20 17:49:06

That's an interesting point, MathIsFun, I never gave that too much thought.
I suppose being aware that jumping ahead may cause some disappointment is
a good thing to be aware of.   Maybe you should eat homemade chocolate chip
cookies and milk to alleviate the confusion that the new material has brought on!

#3396 Re: Help Me ! » Another Question Via Email » 2005-12-20 17:14:11

A five minute analysis on a number line reveals that p=6i±1, and the equation with the 4 is not needed.

#3397 Re: Help Me ! » Finding an inverse function » 2005-12-20 16:37:33

Ricky,  I thought you have to set y=0 for quadratic equation.  Please explain.
Plus, what is the inverse of a function, is it when you swap x and y axis and look
at the graph through the back of the paper, or just look through the back of the
paper and turn 90 degrees??  I can't remember.
...
Okay, I looked up inverses, (x,y) goes to (y,x), so look through back of
paper after flip paper through the y=x slope of 1 axis.
But I still don't understand the use of the quadratic equation with y as a variable and
not y set to zero.

#3398 Re: Help Me ! » Log Question » 2005-12-20 16:29:33

I don't know why, but in post #2 by ryos, the golden ratio
shows up twice.   (√(5) - 1)/2)  and 1.61803

#3399 Re: Help Me ! » 5-Con Triangles? » 2005-12-20 16:03:21

in mathsyperson's generalization, variable b must be closer to 1 than the golden ratio or its reciprocal, 1.618 and .618
So it appears.  if b > 1, then a + ab > ab².
If b < 1, then a < ab + ab²

#3400 Re: Maths Is Fun - Suggestions and Comments » Can we reach for the stars? » 2005-12-20 13:18:27

I've never tried to make a worksheet, maybe I should try that to see how it currently works...
What if I make a worksheet that has mistakes in it or is not using techniques in the right way,
but still ends up working, so it might be not good teaching.  Who will decide what is ypparc
and what is good?  Maybe MSFun will have to approve them?  And I was laughing that a
simple word like the one I spelt backwards was filtered by the filter.  How strange.  Maybe
that word is offensive in Great Britain, but not here 72° west (1/5th of 360°) in New England.
...
Okay I just made a worksheet, but you can delete it because it is all wrong.
I tried to make a Sudoku puzzle but the patterns worksheet was not flexible enough
to draw the boxes of a 4x4 grid or matrix.  Search on Sudoku for title and delete please.

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