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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
    Science Advisor
    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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