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## #1 Re: Help Me ! » Rotation of Conics » 2006-01-05 13:02:09

Yeah it looks just like what I got, and much more accurate.  I never liked drawing elipses.  For the second problem I finnaly figured out how to keep it clean, just use the half angle formulas for the cos and sin values.

## #2 Re: Help Me ! » Rotation of Conics » 2006-01-04 16:57:32

Well I figured out that one, id show what I came up with but I dont have the slightest clue how to show a graph like that on the computer.

New problem now:    2x² - 3xy - 2y² + 10 = 0
a = 2, b = 3, c = -2
plugging it in,  tan2θ = -3/(2 -(-2))    -3/4
using the reference angle from tan-¹ 3/4 I get 2θ = 143.2 so the angle of rotation would be 71.6°
Plugging that into the other forumlas im gonna get a big mess of decimals....
Wonder if there is any way to keep it rationalized????

## #3 Re: Help Me ! » Rotation of Conics » 2006-01-04 12:23:25

Ok I figured it out.  Just had to plug the a b and c values into the Cot2θ = ( a - c ) / b.  Solving for that im getting θ as 30°.  Then I plug it into x = x'cos 30 - y' sin 30 and y = x' sin 30 + y' cos 30.
I simplified them into x = (√(3)x' - y')/ 2   and y = (x' + √(3)y')/2. Plugged them both back into
7x² - 6√(3)xy + 13y² - 16 = 0. And got this for the standard form (x')²/ 4  +  (y')²/1  =  1. Im hopeing that is right.  How would I go about graphing that, im not sure where to start?

## #4 Re: Help Me ! » Rotation of Conics » 2006-01-04 10:47:02

No the whole problem wasnt that but thats the only part I was stuck on, I know the angle of rotation is 45°.  Its just a bad example.  The roatation of an ellipse shows it better.
The equation given is  7x² - 6√(3)xy + 13y² - 16 = 0.  Its an ellipse that is rotated, but im not sure how to find that degree of rotation

## #5 Help Me ! » Rotation of Conics » 2006-01-03 19:35:52

im really bored
Replies: 11

I dont think im really understanding this topic.  For the problem xy - 1 = 0, how do you get the angle of the rotation out of that?

## #6 Re: Help Me ! » Greek Letter » 2006-01-03 19:32:12

All I can get for the synonym of paris is calcium sulfate. (Plaster of Paris). I tried it a few other ways like that, but I dont think the answer has to do with chemistry at all.. Im wondering about any other names paris might have?

## #7 Re: Help Me ! » Greek Letter » 2006-01-03 15:20:49

Yay it fits too, im doing this crossword for chemistry and I dont know half the stuff.
Ive got another one too, what is a synonym for paris(no idea what it had to do with chemistry), 12 letters, and there is a "d" as the seventh letter from the top, unless a carnelian relative isnt sard. I was thinking cityoflights. It fits but no d.  Mabye it isnt sard...

## #8 Re: Help Me ! » Greek Letter » 2006-01-03 14:51:03

dont know, oh and about the question, its what is the name of the greek letter to symbolize angular velocity, and I have no idea what it is

## #9 Help Me ! » Greek Letter » 2006-01-03 12:59:05

im really bored
Replies: 7

What is the Greek letter to symbolize angular velocity?

## #10 Re: Help Me ! » Algebra » 2005-08-26 10:46:09

I think the teachers answer is right, in the order of  operations it goes: parentheses, exponets, multiplication, division, addition, then subtraction. So in the problem first you would put in the given variables, (2(2) + 2(4) / 2(6), then (4 + 8) / 12, then 12 / 12, which simplifys to 1.

## #11 Re: Ganesh's Puzzles » Problems and Solutions » 2005-07-20 19:21:56

Nope no calculas or your method, I just got a tip from a friend that its related to the natural log of 2, which is 0.69314718055994530941723212145818.

## #12 Re: Ganesh's Puzzles » Problems and Solutions » 2005-07-20 11:14:20

For MathIsFuns lake problem I got 6,931,471.8055994530941723212145818 liters of water that needs to be added.

## #13 Re: Puzzles and Games » The truel » 2005-07-19 19:44:39

wow well thats alot to take in at once, I would try and verify mine like you did yours but im just too tired right now.

## #14 Re: Puzzles and Games » The truel » 2005-07-19 19:21:05

In my idea it would put Mr.black and Mr.Gray against each other in the end, that is best possible senario for mine, instead of Mr. black up against Mr. White as the last two to where if you miss Mr. White then you die next shot, but if its upagainst Mr. Gray as in mine, if you miss then there is a chance he might miss too giving you another shot.

## #15 Re: Puzzles and Games » The truel » 2005-07-19 18:12:18

I would shoot at Mr. White because if you shot Mr.Gray and killed him Mr. White would go next and always hits the person so you would be dead, but if you shoot Mr.White and hopefully kill him, you go up against Mr. gray who only hits it 2/3 of the time so he might miss giving Mr. Black another shot against Mr. White.

## #16 Re: Dark Discussions at Cafe Infinity » Serious Discussion! » 2005-07-19 08:23:33

In my opinion the death penalty doesnt just include lethal injection, the chair ect. but also includes life sentences because either way you are going to die for your crime, such as the state I live has no death penalty but a few months ago when a man was convicted of some horrible crimes, I wont say what, he was given I think 1300 some years in prison without bail. So what would be worse, knowing you are gonna die right then and there, or knowing you will never leave the prison you are in and will live there and die there no matter what.

## #17 Re: This is Cool » Mathematic complexity » 2005-07-18 03:47:57

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## #18 Re: This is Cool » Mathematic complexity » 2005-07-17 20:05:54

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## #19 Re: This is Cool » Mathematic complexity » 2005-07-17 19:18:55

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## #21 Re: This is Cool » Mathematic complexity » 2005-07-17 19:11:24

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## #22 Re: This is Cool » Mathematic complexity » 2005-07-17 19:08:50

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## #23 Re: This is Cool » Mathematic complexity » 2005-07-17 19:05:36

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## #24 Re: This is Cool » Mathematic complexity » 2005-07-17 19:02:33

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## #25 Re: This is Cool » Mathematic complexity » 2005-07-17 18:54:49

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