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Math Help - Please help

  1. #1
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    Please help

    I am taking pre-cal at our local college and have my final on monday. The teacher gave us a study guide but I am having a few problems and need some help please. I am stuck on these two problems:
    solve algebraically between [0,2pie]
    2cosx +Sq. root2=0

    other problem: solve for x
    arccos x- arccot6/5=0


    Can someone please show me how to work these. I am sure we went over it in class but I am lost. Thank you
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  2. #2
    o_O
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    #1:
    Isolate cos(x):
    \begin{array}{rcl} 2\cos x + \sqrt{2}  & = & 0 \\ 2\cos x & = & -\sqrt{2} \\ \cos x & = & -\frac{\sqrt{2}}{2}\end{array}

    Now I'm sure you've gone what values of x would work to solve the last line.

    #2:
    \begin{array}{rcl} \arccos x - \text{arccot} \left(\frac{6}{5}\right) & = & 0 \\ \arccos x & = & \text{arccot} \left(\frac{6}{5}\right) \\ x & = & \cos \left[ \text{arccot} \left(\frac{6}{5}\right) \right] \end{array}

    In that last line, I basically took the cosine of both sides. You would need a calculator for this as I doubt you know the exact value of \text{arccot} \left(\frac{6}{5}\right).
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  3. #3
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    Thanks for the help. I will see what I can do.
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