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Differential Equation

  1. Nov 16, 2011 #1
    I am having trouble Differentiating the following with respect to ∅. Can you show me the steps I need to take to get the given correct answer please.

    z = ((A+B)/2) + ((A-B)/2)Cos2∅ + C Sin2∅


    The correct answer is
    Tan2∅ = (2C)/(A-B)
     
  2. jcsd
  3. Nov 16, 2011 #2
    for your answer to be true, dz/d(theta) has to equal zero.

    differentiating: dz/d(theta)=0-(A-B)sin(2∅)+2Ccos(2∅)
    if dz/d∅=0, then divide by cos(2∅) on both sides and you'l get

    0=-(A-B)tan(2∅)+2C

    solve for tan and you'll get tan(2∅)=(2C)/(A-B)
     
  4. Nov 17, 2011 #3
    Thanks Physeven
    can you explain to me in more detail how you got the line
    please. Its the actual process of differentiation I am having trouble with.

    dz/d(theta)=0-(A-B)sin(2∅)+2Ccos(2∅)
     
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