Linearising Cosine: Taking Roots of Equation

  • Thread starter Agrajag
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In summary, linearizing an equation means finding the closest linear approximation to a given curve. This can be done by taking the derivative at a point, which represents the slope of the line passing through that point. The final equation should be in the form y=mx+c, with y representing I(theta) and x representing theta.
  • #1
Agrajag
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Homework Statement


Linearise the following equation I(theta) = (I1 – I2 ) cos (2theta) + I2
where I1 and I2 are constants.

Homework Equations


I(theta) = (I1 – I2 ) cos (2theta) + I2

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?
 
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  • #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.
 
  • #3
friendbobbiny said:
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.

Hi friendbobbiny, the final equation should be in the form y=mx+c where y is I(theta) and x is theta.
 
  • #4
Agrajag said:
Hi friendbobbiny, the final equation should be in the form y=mx+c where y is I(theta) and x is theta.

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)?
 

1. What is the purpose of linearising cosine?

Linearising cosine involves transforming a non-linear equation into a linear one in order to make it easier to solve. This is particularly useful in calculus and physics, where linear equations are easier to manipulate and analyze.

2. How do you linearise cosine?

To linearise cosine, you need to use the trigonometric identity cos(x) = 1 - sin^2(x). This allows you to replace cosine with a quadratic equation in terms of sine, which can then be simplified and solved.

3. Can any cosine equation be linearised?

No, not all cosine equations can be linearised. Only equations that involve a single cosine term can be linearised using the method described above. More complex equations, such as those with multiple cosine terms or other trigonometric functions, may require different techniques to linearise.

4. Why is it beneficial to take the roots of a linearised cosine equation?

Taking the roots of a linearised cosine equation allows you to solve for the values of x that satisfy the original equation. This can be useful in finding solutions to real-world problems, as well as in verifying the accuracy of mathematical models.

5. Are there any limitations to linearising cosine?

Linearising cosine is a useful technique, but it does have some limitations. It may not always produce exact solutions, and it may not be applicable to more complex equations. It is important to carefully consider the problem at hand and determine if linearising cosine is the best approach.

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