Math Is Fun Forum
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#651 Re: Help Me ! » more than one way ... » 2006-11-28 08:11:59
ah, i see.
so in this case
take a guess at 4
is this method better than the +/- one, where you take two points on opposing sides of the x axis, and iteratively subdivide to gain another 1dp of accuracy? This method does seem to suffer from the same fatal flaws like the iteration one where you can only really find one root, and doesnt always work?
ye............. I would never have been able to explain this to you, good thing you figured that out yourself, I really don't understand any of this.
#652 Re: Help Me ! » hi » 2006-11-28 07:53:35
Yep 
, and you should probably round 'x' up to 11.
#653 Re: Help Me ! » hi » 2006-11-27 15:46:36
You can use the Sine Rule, providing you have learnt it.
(en.wikipedia.com/wiki/sine_rule)
The rule is that one side length over its sine of the opposite angle is proportionate to another side length over the sine of its opposite angle.
Now, I'm assuming the longest side is the hypotenuse and the bottom one is x.
Cross multiply to find x, then repeat for y.
There is another way if you haven't learnt the Sine Rule, but it takes a lot of working:
It is shown in the image attached.
Create an imaginary square around the triangle and fill in all the missing angles, then you can use trigonometry to work out the side lengths.
#654 Re: Guestbook » uhhh » 2006-11-27 02:30:05
#655 Help Me ! » Cuboid inside parabola help please » 2006-11-27 02:22:04
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- Replies: 1
A cuboid needs to be moved through the arch of the equation
.Consider the rectangular cross-section of the cuboid where the top corners of the rectangle touch the arch where the top corners of the rectangle touch the arch and the bottom of the rectangle is on the x axis. Let 'a' metres be the distance from the edge of the arch at the base (the origin) to the nearest edge of the rectangle.
The units on the axes are in metres.
i)Find the height and width of the rectangle when of the rectangle when a = 0.5
I got h=2.5m and w=2m.
ii)Find the height of the rectangle when its width is 2.5 metres.
I got h=1.375m
iii) Find, using an algebraic method, the width of the rectangle when its height is 4 metres.
I got 
.
I attached the image at the bottom.
Thanks.
#656 Re: Help Me ! » Logs » 2006-11-27 02:02:54
Oh dear, you didn't include the brackets in the first question? 
Oh well, good job on completing the question.;)
P.S. I'll still try and get back to you on
#657 Re: Help Me ! » Logs » 2006-11-26 19:32:50
Well, I can't ask him again till Thursday 
.
Try just analysing the graphs of
and
see if you can come up with something
#658 This is Cool » Golden Ratio? » 2006-11-26 19:25:20
- Toast
- Replies: 2
So I was bored and decided to stuff around in paint (yes i know, I was pretty bored), I started with a circle, added a midpoint, then made all kinds of links and connections to come up with what is attached.
Then I noticed that the rectangles sorta looked familiar. Are they the golden ratio??? 
#659 Re: Help Me ! » Logs » 2006-11-26 18:56:39
Hi Thatcher, I just asked one of my friends and he said it is unsolvable using logs. He said you need to use calculus, which I haven't learnt.
Either by graphing or using a calculator I got x ≈ 0.563895524260.
A forum member should come along soon and help you with the method though, don't worry.
#661 Re: Maths Is Fun - Suggestions and Comments » Private Messaging » 2006-11-25 23:44:13
Thanks everyone, I'd like to be a real member
Rida should be one too
#662 Re: Help Me ! » One quick question...help thanks! » 2006-11-25 18:53:00
That question implies the golden ratio, which is equal to approximately 1.618, but which really keeps going forever.
Try this link:
http://en.wikipedia.org/wiki/Golden_ratio
It gives you quite an interesting read on it, albeit possibly hard to comprehend, and if you scroll down, it shows you how to calculate it.
#663 Re: Maths Is Fun - Suggestions and Comments » Private Messaging » 2006-11-25 15:15:50
Well, I haven't exactly been around for that long... compared to posters like jU, so I wouldn't at all mind staying as a full member for now, I just posted this topic out of curiosity really.
#664 Re: This is Cool » 0.9999....(recurring) = 1? » 2006-11-25 05:48:25
Why can't you all just call it undetermined and leave it be like how they dealt with
?#665 Help Me ! » Check working » 2006-11-25 00:22:10
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- Replies: 0
Can someone please check my working and answers for these, I'm not confident I got them right
http://www.mathsisfun.com/forum/viewtopic.php?id=5169
#666 Re: Exercises » Areas and Volumes (Moderate difficulty) » 2006-11-24 21:38:37
Ok, firstly, these answers are not complete *YET*. This means two things,
a) Don't expect to find everything here
b) Until they are thoroughly checked, *RELY ON THEM AT YOUR OWN RISK*
ANSWERS
Thanks for the corrections Kurre, I had a feeling I was wrong. I've resubmitted Q.2 with different values.
#667 Re: Jokes » Funny Pictures!!!!! » 2006-11-24 16:46:30
LOL Funny!
#668 Re: Guestbook » Hey all » 2006-11-24 16:26:11
Mmmmm, wish we had thanksgiving, I wouldn't mind an extra turkey every year...
#669 Re: Jokes » The Top Ten Excuses for Not Doing Any Homework » 2006-11-24 06:02:02
Smart would know not to use them, and well, the rest probably wouldn't know them in the first place. That means that they are applicable to nobody.
#670 Re: Guestbook » math » 2006-11-24 01:58:32
That's great
#671 Re: Maths Teaching Resources » Crazy Teachers » 2006-11-24 01:54:23
...but my 3nglish t3acher 3xists
#672 Exercises » Areas and Volumes (Moderate difficulty) » 2006-11-24 01:49:40
- Toast
- Replies: 2
*Problems uploaded as JPEGs at the bottom of this post*
So, these are actually harder than the thread title says (sorry). These are all solid geometry problems.
If you want, answer all in exact simplified form before finding the decimal approximation.
Accuracy is key.
(If question 3 is too much of a pain don't attempt it)
I'll be uploading more soon.
#673 Re: Puzzles and Games » Conundrums » 2006-11-22 23:04:42
sounds like a very popular show , too bad we don't really have anything like that in Australia, just quick quizzes and luck games.
#674 Re: Help Me ! » What's an inverse function? » 2006-11-22 22:53:13
thanks, but nevermind lol I don't really understand what you're talking about
#675 Help Me ! » What's an inverse function? » 2006-11-22 17:47:50
- Toast
- Replies: 5
This term seems to be used a lot in the website, but I can't say i've heard it mentioned in class.
Please explain and give an example.