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anonymous

  • 5 years ago

Can anyone help me parametrize sin(x)*e^y=0?

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  1. anonymous
    • 5 years ago
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    The solution is Pi

  2. anonymous
    • 5 years ago
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    i want to find a parametrization though. You know, x^2+y^2=1, the parametrization is x=cos(t) y=sin(t)

  3. anonymous
    • 5 years ago
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    Check this out. http://tutorial.math.lamar.edu/Classes/CalcII/ParametricEqn.aspx

  4. anonymous
    • 5 years ago
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    You mean, you want the parametric equations?

  5. anonymous
    • 5 years ago
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    so you mean parametrize z= e^(y)sin(x)

  6. anonymous
    • 5 years ago
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    yes chaguanas, i just cant seem to find a relation between x and y, or such. and im checking the link now, murph. thx

  7. anonymous
    • 5 years ago
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    the thing is, the link tells you more about how to reverse a parametric eqn than how to make one. Right now, I can't find a relation; i.e. I can't parametrize in polar coordinates nor in spherical coordinates.

  8. anonymous
    • 5 years ago
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    ok, the whole question is: find parametric eqns for the three level curves of the function W(x,y)=sin(x)e^y which pass throught the points... well, I found one level curve z at z=0 to be sin(x)e^y=0, so I need to parametrize it.

  9. anonymous
    • 5 years ago
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    You need to post the whole question. Because you are not giving us enough info, and even misinterpreting the question.

  10. anonymous
    • 5 years ago
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    ok, "find parametric eqns for the three level curves of the function W(x,y)=sin(x)e^y which pass throught the points P=(0,1), Q=(pi/2,0) and R=(pi/6,3). Also compute the vectors of the gradient vector field W at the points P, Q, and R."

  11. anonymous
    • 5 years ago
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    I know how to find the gradients, so im more concerned with the first part.

  12. anonymous
    • 5 years ago
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    I think you find the dell or gradient, which is a vector, and use that vector in conjunction with the points to find parametric eq

  13. anonymous
    • 5 years ago
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    but the gradient only shows change, how can it help me parametrize?

  14. anonymous
    • 5 years ago
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    I dont think you can parametrise, end of story

  15. anonymous
    • 5 years ago
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    well, it is a homework question. i don't think the books wrote all that for nothing

  16. anonymous
    • 5 years ago
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    i do

  17. anonymous
    • 5 years ago
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    Be careful with the word parametrise, that was your previous lesson. The gradient are normal to the level curve. You want to find the parametric eq.

  18. anonymous
    • 5 years ago
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    i still don't understand, how is the gradient going to help me?

  19. anonymous
    • 5 years ago
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    It is going to give you a vector. The vector is used in conjunction with the points to find the parametric eq.

  20. anonymous
    • 5 years ago
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    can you tell me how?

  21. anonymous
    • 5 years ago
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    Partial derivative in relation to x, partial in relation to y

  22. anonymous
    • 5 years ago
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    yes i know, what do you do with the gradient after that?

  23. anonymous
    • 5 years ago
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    let's say the vector is <1,2> and point P (0,1). Parametric eq is x=0 + 1t, or x=t y=1+2t

  24. anonymous
    • 5 years ago
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    ok, so the vector at (0,1) comes out to <e,0>. so parametric is x=e*t, y=1? That doesn't come out right.

  25. anonymous
    • 5 years ago
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    Don't solve for the vector at (0,!). Just get the vector from the partial fractions. You are anticipating and reading too much into the question.

  26. anonymous
    • 5 years ago
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    wait so what is the vector?

  27. anonymous
    • 5 years ago
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    Just find the partial derivative in relation to x, partial in relation to y. You already said you know how to do it. In fact, you have already done it. But apparently you made an extra step and put in (0,1).

  28. anonymous
    • 5 years ago
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    yeah, but im supposed to somehow use that to parametrize? ok, so i got the gradient and it's <cos(x)e^y, sin(x)e^y>

  29. anonymous
    • 5 years ago
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    For the rest of your life, don't use the word parametrize. You are not parametrizing. You are finding the parametric equations.

  30. anonymous
    • 5 years ago
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    sorry. ok, so how do you use <cos(x)e^y, sin(x)e^y> to find the parametric equations?

  31. anonymous
    • 5 years ago
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    \[x =t e ^{y} \cos x\]\[y =1+te ^{y}\sin \]

  32. anonymous
    • 5 years ago
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    and that's for a general level curve?

  33. anonymous
    • 5 years ago
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    so what is the parametric eqn for z=0?

  34. anonymous
    • 5 years ago
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    Post your question again, as a new post, this time the whole question; so you can get a fresh perspective from some other guys.

  35. anonymous
    • 5 years ago
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    yeah, thx for your help!

  36. anonymous
    • 5 years ago
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    most ppl here dont know multivariable calc though

  37. anonymous
    • 5 years ago
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    One or two of them do. There is someone named Lokisan who comes on at odd hours and goes through all pass questions and sends a response.

  38. anonymous
    • 5 years ago
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    I think I got it. plug in values for P in your original eq. I think it gives your 0. So one of your level curve is sinxe^y=0. Do it for the other two points. Then find parametric eq of each.

  39. anonymous
    • 5 years ago
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    yes, that was exactly my original question, which was "find the parametric equation of sin(x)e^y=0", but I just couldn't find a parameter that satisfies the equation

  40. anonymous
    • 5 years ago
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    *parametric equations

  41. anonymous
    • 5 years ago
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    Finding parametric equations is a very simple process. Use partial fractions to get a vector, and with that vector and the point find values of x and y, (the answers include t)

  42. anonymous
    • 5 years ago
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    you did that for me before, but so what is the vector? I got the gradient, so what do you want me to do with it?

  43. anonymous
    • 5 years ago
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    where did you go?

  44. anonymous
    • 5 years ago
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    i lost the post, this is moving so fast

  45. anonymous
    • 5 years ago
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    hahaha, scroll down a bit more

  46. anonymous
    • 5 years ago
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    computer wont let me

  47. anonymous
    • 5 years ago
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    listen, im not trying to take sides because I don't even worship a god. However, i'm just saying that everything happens for a reason. If something happens, don't look to god. look to another reason. That's why they got meterology and all that what not, right?

  48. anonymous
    • 5 years ago
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    yeah

  49. anonymous
    • 5 years ago
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    whats this about worshipping the laws of nature. we dont even know the laws of nature are permanent

  50. anonymous
    • 5 years ago
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    physics? yes, it is. are you saying that gravity is not permanent, that it does not equal 9.8m/s^2 when close to Earth's surface?

  51. anonymous
    • 5 years ago
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    right, we dont know what will happen in the future

  52. anonymous
    • 5 years ago
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    there is no reason to prevent gravity from ceasing, mass will cease, etc , in the next instant

  53. anonymous
    • 5 years ago
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    just because our "laws" have described nature in the past, who is to say what will happen in the future

  54. anonymous
    • 5 years ago
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    science works until it stops working, so to speak. and then we try something else

  55. anonymous
    • 5 years ago
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    but there arent any real laws. or permanent

  56. anonymous
    • 5 years ago
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    everything changes

  57. anonymous
    • 5 years ago
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    yes, i suppose that if god decides to change the laws of physics, then he will. however, for now, earthquakes will always occur when a tectonic plate happens to accidentally brush up against another one, and fires will keep on reacting as long as there is oxygen to fuel it, and babies cannot be magically lifted into the air without any physics behind it

  58. anonymous
    • 5 years ago
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    nothing can be done, nor should be done, to change that. or else there will be devastating consequences

  59. anonymous
    • 5 years ago
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    no i mean, aside from god

  60. anonymous
    • 5 years ago
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    even if god doesnt exist, the laws of nature can spontaneously change. what is there to provent that?

  61. anonymous
    • 5 years ago
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    actually, god's existence could be arguably a reason that gravity will not cease. he is there to prevent it. but i dont see any evidence for god. so we are truly floating blindly in space , and our laws have no permanence

  62. anonymous
    • 5 years ago
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    that's philosophy. out of my range, out of the range of mathematics too, within which we are posting =D but, science has worked for hundreds of thousands of years, and it doesn't seem to be changing now, so why should it?

  63. anonymous
    • 5 years ago
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    why should it not . actually there is a reason why it should. empirically everything changes

  64. anonymous
    • 5 years ago
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    oh i hope i didnt contradict myself

  65. anonymous
    • 5 years ago
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    if you can find one, (outside of quantum mechanics, and any other science that is still developing) I should like to know it

  66. anonymous
    • 5 years ago
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    can find what? an example of a law changing, oh

  67. anonymous
    • 5 years ago
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    well then science will just have to modify things a bit

  68. anonymous
    • 5 years ago
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    the only reason why science works in the first place is because there is consistency in the universe, regularity, repeatability. if we lose this regularity (doesnt matter what it is), then science wont work . you cant frame a law of nature if there is nothing for it to express , if nothing is predictable

  69. anonymous
    • 5 years ago
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    youre right though, this is outside the scope of math problems

  70. anonymous
    • 5 years ago
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    if we lose a regularity, then we search further, because we can always assume there is a regularity in the universe. Even "regularity" cannot be strictly defined. what occurs often is regularity, sometimes things that are irregular in the beginning become regular as we understand it more

  71. anonymous
    • 5 years ago
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    hence, quantum mechanics and the such

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