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Homework Help: Setting Up an Advanced Mathematics Equation

  1. Sep 22, 2013 #1
    1. The problem statement, all variables and given/known data
    Twice the supplement of angle 0 is 104 degrees greater than four times the complement of angle 0. Find 0.

    2. Relevant equations

    3. The attempt at a solution
    I'm not sure where to begin. I'm good with angle relationships, all I need is the equation.
  2. jcsd
  3. Sep 22, 2013 #2

    Andrew Mason

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    You could begin by writing an equation for the supplement and the complement of an angle θ. Then substitute in the equation that you are given:

    2s = 4c + 104

  4. Sep 22, 2013 #3
    Thank you!
  5. Sep 22, 2013 #4
    So the next step would be to divide both sides by 4, yielding 2s=c+26 . Then I could divide both sides by 2, yielding s=c+13. After that,I'm not sure how to proceed, because I still don't know c.
  6. Sep 22, 2013 #5

    Andrew Mason

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    Use the definition of supplementary and complementary angles. But check your algebra first! You have to do the same operation to BOTH sides of the equation.

  7. Sep 22, 2013 #6
    I could divide all the things by 2, yielding s=2c+52, but then I don't know what to do with the 2c.
  8. Sep 22, 2013 #7

    Andrew Mason

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    What is the definition of supplementary angle in terms of θ? What is the definition of complementary angle in terms of θ?

  9. Sep 22, 2013 #8
    I could divide 52 by 2c, but then all I have is s=26c.
  10. Sep 22, 2013 #9
    Oh! Sorry! I was too busy working on randomly dividing that I forgot to check for new replies.
  11. Sep 22, 2013 #10

    Andrew Mason

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    You have to follow the rules of algebra first. You must do the same operation to both sides of the equation.

    Use s = 2c + 52

    s = ? (an expression involving θ)
    c = ? "

    That gives you a single equation with one unknown: θ, so you have the solution.

  12. Sep 22, 2013 #11
    Okay, I know that complementary angles add up to 90 degrees, and supplementary angles add up to 180 degrees, but I'm not sure how to work that into the equation. 2s=180=4c+104 doesn't seem to make sense.
  13. Sep 22, 2013 #12
    Annnnd again. xD. I need to refresh the page more often.
  14. Sep 22, 2013 #13
    Okay, so I have s=c+52 But I'm not quite sure what to do with my information about complementary and supplementary angles. 180-s=90-c+52 *seems* right, but that introduces more numbers and symbols that don't seem to want to go anywhere.
  15. Sep 22, 2013 #14
    So you have some angle ##\theta##. If ##s## is its supplementary, what is it? Write this as a formula ##s = ... ##, where ##...## has ##\theta## in some (correct!) way.
  16. Sep 22, 2013 #15
    Would something along the lines of 0=(180-s=90-c+52) work out somehow? It doesn't seem right. Sorry for the trouble, I'm used to applying equations, not writing them.
  17. Sep 22, 2013 #16
    Or 0+s=90-c+52 ?
  18. Sep 22, 2013 #17
    You said: "supplementary angles add up to 180 degrees". If the supplementary angles are denoted by ##\theta## and ##s##, write "supplementary angles add up to 180 degrees" as an equation involving ##\theta, \ s ## and 180 degrees.
  19. Sep 22, 2013 #18
    Thank you! So write that equation, abandoning this one?
  20. Sep 22, 2013 #19
    You do not need to abandon your previous work just yet. What you need, to continue, is to obtain equations that relate ##\theta## with ##s##, and ##\theta## with ##c##. Then you come back to your previous work.

    The equations I am talking about follow directly from the definitions of supplementary and complimentary angles, which you know. You just need to write those definitions down algebraically.
  21. Sep 22, 2013 #20
    Or incorporate it into the old? Possibly s+0=180=c+52 ?
  22. Sep 22, 2013 #21
    Oops, we posted at the same time. Is something like the above equation correct?
  23. Sep 22, 2013 #22

    Andrew Mason

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    Check the definition of complementary angles.

    I suggest you take a step back and go through all of our suggestions and study the problem again. Be very careful with your algebra. You should be able to solve this problem now. You need to figure it out for yourself now.

  24. Sep 22, 2013 #23
    Do not incorporate anything into anything just yet. Work out your basic equations first. You have not done so, at least here, despite our requests.
  25. Sep 22, 2013 #24

    Thanks, AM. Is that what you meant?
  26. Sep 22, 2013 #25
    Okay. Sorry, it is somewhat confusing working with two people at the same time. I'm not sure I understand the requests as you meant them. Voko, when AM left off right before you came in, we had s=c+52
    Would you mind restating the next step?
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