Math Is Fun Forum
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#276 Re: Maths Is Fun - Suggestions and Comments » Multiplication Tables (New Page) » 2007-01-19 21:32:25
I only ever learnt my tables to 12*12, I don't think it's necessary to learn past that
#277 Re: Guestbook » This Is Site Awesome! » 2007-01-19 07:17:31
Thanks Emily 
I can see you tried to type in caps XD
#278 Re: Puzzles and Games » ^_^ » 2007-01-19 07:16:27
I do not understand.
#279 Help Me ! » Proving the Pythagorean Identity » 2007-01-18 22:40:41
- Toast
- Replies: 4
I checked on Wikipedia but all they gave was:
So:
But I don't see how the right side relates to 1?
#280 Re: This is Cool » Vote for Your Favorite Math T-Shirt » 2007-01-18 20:10:59
I like the inifinity one
#281 Re: Dark Discussions at Cafe Infinity » I wrote this song this morning. » 2007-01-18 02:09:04
Hmm, I haven't heard much like this before. I'm still trying to play it fast but it's kinda confusing 
. I guess it would sound good played fast. How is it based on Ganesh's number?
#282 Re: Help Me ! » Whats X » 2007-01-17 05:10:16
Well, I forgot how to prove this, but if a triangle resides in a circle so that one of its sides is the diameter and all vertices rest on the circumference, then the angle opposite the diameter will always be 90 degrees.
So, in BDC, since BD is the diameter, angle C must be 90 degrees.
Let's call the complementary angle of x 'y'. Angle y is part of Triangle ABC. Since AC is the diameter, angle B must equal 90 degrees. Hence, angle y = 180-45-90=45 degrees.
As y is complementary to x (y+x=90), x = 90-45 = 45 degrees.
#283 Re: Help Me ! » Help » 2007-01-17 05:02:15
I would say segment LM is twice the length of OK. This is assuming that O is the centre of the circle (if it isn't then I might be wrong).
This is because:
OK is the radius, as its endpoints are the centre O and the circumference.
LM is the diameter, as it passes through the centre O and its endpoints reside on the circumference.
And Diameter = Radius * 2
#284 Re: Help Me ! » Help » 2007-01-17 04:53:12
Did you save it as a JPEG? Make sure it is saved as a JPEG when you upload it. To make it a JPEG, open it in Microsoft Paint, click save as..., then there will be a scroll down selection box, with various file formats. Select JPEG and save. Then uploading it should work (as long as it's the right size too, if it isn't then u must resize it)
Just in case:
To upload, scroll down a little and there should be 'Image Upload'. Select 'Show 1 Upload Slots', then browse your documents to find the file path.
#285 Re: Help Me ! » Help Me Urgently » 2007-01-17 04:51:11
You know that the father is presently 30 times older than his son, so
1. x = 30y
You also know that in 18 years time he will be 3 times as old as his son
2. x+18=3(y+18)
(You have to add 18 years to x and to y)
Since x = 30y
You can substitute x into equation 2:
30y+18=3(y+18)
30y+18=3y+54
27y=36
y=1.3333...
Hence the son is presently 1 and 1/3 years old
Since y = 1.3333...
x = 30(1.333...)
x = 40
Hence the father is presently 40 years old.
#286 Re: Help Me ! » A Train........... » 2007-01-17 04:42:14
Mathsy's answer is probably correct...
Speed = Distance/Time
= 350/20
= 17.5
Train runs at 17.5m/s.
If you want convert into km/h:
(17.5*60*60)m/h
((17.5*60*60)/1000)km/h
=63km/h
I think the length of the train is irrelevant. It depends on whether the train starts on the bridge or not. My answer is based on the assumption that the nose of the train is touching the start of the bridge.
#287 Re: Help Me ! » Help Me Urgently » 2007-01-17 04:37:34
You can derive this equation:
Let X = Father's age
Let Y = Son's age
1. x = 30y
2. x+18=3(y+18)
Substitute 1 into 2 to get
30y+18=3(y+18)
Solve for y, then substitute the y value into eq.1
#288 Re: Guestbook » please reply » 2007-01-17 01:27:30
Yeah, I've got kangaroos hopping all around my garden and the parks, and I live in the suburbs!
#289 Re: Dark Discussions at Cafe Infinity » I wrote this song this morning. » 2007-01-16 17:05:05
Thanks, but yeah, I'm not really familiar with reading music like that, so a bitmap would be great.
#290 Re: Guestbook » please reply » 2007-01-16 06:56:03
Somebody please direct me where this thread is going, I am quite lost and there are no road signs anywhere.
#291 Re: Guestbook » Horray!!!!!!!!!!!!!!!!!! (and is cool cat there?) » 2007-01-16 06:40:14
Where do all the rest fit on that ladder?
#292 Re: Guestbook » yo » 2007-01-16 06:38:35
Hello.
#293 Re: Jokes » susie » 2007-01-16 06:34:45
Preaty good!
Such a display of huspamity hath mine eyes never before bore witness to. 
(Hope my sentence makes sense)
(Nope, don't think it does)
#294 Re: Dark Discussions at Cafe Infinity » I wrote this song this morning. » 2007-01-16 06:29:03
I still don't know how to interpret it 
#295 Re: Guestbook » please reply » 2007-01-16 06:23:03
'tis an aeroplane!
#296 Re: Jokes » delhi....mumbai » 2007-01-16 06:17:50
Nice joke. Post Master got OOOOOWWWWNNNNNEEEEEEEEEDDDDDDDD!!!
#297 This is Cool » Math/Science Magazines » 2007-01-15 20:45:04
- Toast
- Replies: 3
What are the best math or science related magazines out there? A friend of mine lent me some editions of the 'New Scientist' magazine and they were very interesting but I remember hearing of some others as well.
#298 Re: Puzzles and Games » Tricky puzzles » 2007-01-15 07:34:39
Fire.
I posted that riddle in my own topic.
Sorry I must have missed it
I never was, and I'm always to be,
Nobody ever saw me, or ever will,
However, I am the confidence of all
Who live and breathe on this earth.
What am I?
#299 Help Me ! » Painting Apartment Blocks » 2007-01-14 19:50:40
- Toast
- Replies: 3
A painter is employed to paint an apartment block. The owner of the apartment block tells the painter that there are certain conditions as to how the floors of the apartment block can be painted.
- Each floor must be either blue or red.
- No two adjacent floors can both be blue. However they can both be red.
If
is the number of different ways an apartment block of n floors can be painted, express in terms of and .Prove your answer.
---------------------------------------------------------------------------------------------------
So I drew this diagram, and so far the diagram is the only way I have been able to count how many ways the floors can be painted in.
Using the diagram, I found and , so .
Now it asks me to prove it. How would I go about writing a proof for the formula?
Also, is there any other way to find the number of floors without initially using a diagram?
Thanks.
#300 Re: Help Me ! » help on this please » 2007-01-14 19:24:40
Perhaps they will think you are gifted cuz you don't need to study to do well in an exam lolz