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Homework Help: Linearising cosine

  1. Oct 14, 2015 #1
    1. The problem statement, all variables and given/known data
    Linearise the following equation I(theta) = (I1 – I2 ) cos (2theta) + I2
    where I1 and I2 are constants.

    2. Relevant equations
    I(theta) = (I1 – I2 ) cos (2theta) + I2

    3. The attempt at a solution
    Not sure how to linearise the cos(2theta). Have tried trig identities, would the best option be to take roots of both sides of the equation?
  2. jcsd
  3. Oct 14, 2015 #2
    Hi Agrajag, what do you mean by linearize? I usually understand "linearization" to mean: find the closest linear approximation to the given curve. This can be found by taking the derivative at a point to be the slope of a line that goes through that same point. This line is your linearization.
  4. Oct 14, 2015 #3
    Hi friendbobbiny, the final equation should be in the form y=mx+c where y is I(theta) and x is theta.
  5. Oct 14, 2015 #4
    In that case, my approach works! Have you read into finding a linearization by taking a derivative at some point of interest (or at any point of interest)?
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