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Homework Help: Solve for theta

  1. Oct 21, 2008 #1
    1. The problem statement, all variables and given/known data
    1 - 2sinθ - 3cosθsinθ = 0

    2. Relevant equations

    3. The attempt at a solution
    first i replaced cosθ with sprt(1 - sinθ) but that appears to give me a crazy algebra problem.
    then i tried replacing 3cosθsinθ with 3cotθ(sinθ )^2 but that doesnt get me anywhere.

    i must be forgetting something. is there an easy way to solve this? or am I just going to have to deal with the excessive algebra?
  2. jcsd
  3. Oct 21, 2008 #2


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    Staff Emeritus
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    Gold Member

    What's so crazy about it? It looks uncomplicated to me, and of the type you've probably spent an entire chapter (or at least section of a chapter) practicing how to solve.

    (By the way, don't forget that (1 - sin² θ) has two square roots)

    (By the way, answers required to be exact?)
  4. Oct 21, 2008 #3
    well i just came across this in Engineering Mechanics. I thought maybe there was an easier way that I forgot about. I guess not, I'll be able to do it, its just gunna be a pain lol
  5. Oct 22, 2008 #4
    Do you need an exact solution? If not just graph the equation and identify the zero's. There appear to be 2 soln's between 0 and 2pi.
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