What is the average for cos2(x)?

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In summary, <cos^2(theta)> is calculated using the formula cos^2(theta) = (cos(theta))^2, which means squaring the cosine value of the given angle. The range of values for <cos^2(theta)> is from 0 to 1, and it cannot be negative. This value is related to the unit circle as the squared distance of a point on the unit circle from the x-axis. It cannot be greater than 1, as the value of cosine cannot be greater than 1.
  • #1
ucbugrad
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What is the expectation value of cosine squared, namely <cos^2(t)>?
 
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  • #2
cos2x = (1+cos(2x))/2

Integration leads to 0,5 (averaged over the lenght)
 
  • #3
Another approach: cos2(x) + sin2(x) = 1. Both terms have the same average, so the average for cos2(x) = 1/2.
 

1. How do you calculate ?

To calculate , you can use the formula cos^2(theta) = (cos(theta))^2. This means that you square the cosine value of the given angle.

2. What is the range of values for ?

The range of values for is from 0 to 1. This means that the value of will always be between 0 and 1, inclusive.

3. Can be negative?

No, cannot be negative. Since it is the square of the cosine value, it will always be a positive number or 0.

4. How is related to the unit circle?

is related to the unit circle as it represents the squared distance of a point on the unit circle from the x-axis. This distance is also known as the cosine value of the angle on the unit circle.

5. Can be greater than 1?

No, cannot be greater than 1. Since the value of cosine cannot be greater than 1, the squared value of cosine will also not be greater than 1.

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