Orthogonality of Sine and Cosine functions

In summary, to evaluate a function using orthogonality means to use the six formulas provided in the first paragraph of the link given. In this case, it involves finding the coefficients in a Fourier series using equations (8), (9), (18), and (19) and using the fact that sine and cosine terms are orthogonal in the integral.
  • #1
Hendrick
43
0
Hi,

would anyone be able to explain how to evaluate a function using orthogonality (i.e. using orthogonality to solve a definite integration problem with sines/cosines)?

Thank you
 
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  • #3
Orthogonality in a vector space means that the inner product of two vectors is 0. In this case, your space is a function space so the inner product is defined as the integral of the product of the functions.

http://en.wikipedia.org/wiki/Orthogonal#Orthogonal_functions
 
  • #4
I would look in (already referenced in post #2 By ExactlySolved)
http://mathworld.wolfram.com/FourierSeries.html
And in particular look at Eqns (8) and (9) for solving for the coefficients in a Fourier series. Also look at (18) and (19). The sine-like and cosine-like terms are orthogonal, as proved by integrating their product over the interval 0 to 2 pi.
 

1. What is the definition of orthogonality of sine and cosine functions?

The orthogonality of sine and cosine functions refers to the property that these two trigonometric functions are perpendicular to each other when graphed on a coordinate plane. This means that the area under their product over a specific interval is equal to zero.

2. How is the orthogonality of sine and cosine functions used in mathematics?

The orthogonality of sine and cosine functions is used in various mathematical concepts such as Fourier series, which is used to represent periodic functions as a sum of simple sine and cosine functions. It is also used in solving differential equations and in applications such as signal processing and image analysis.

3. Can you explain the geometric interpretation of orthogonality of sine and cosine functions?

The geometric interpretation of orthogonality of sine and cosine functions can be visualized by graphing these two functions on a coordinate plane. The point where the two functions intersect represents the origin (0,0) and the angle between the two functions is 90 degrees, making them perpendicular to each other.

4. Are there any other functions that exhibit orthogonality?

Yes, there are other functions that exhibit orthogonality, such as the sine and cosine functions in complex analysis, where they are used to form a basis for complex Fourier series. Other examples include Legendre polynomials, Bessel functions, and Chebyshev polynomials.

5. How is the orthogonality of sine and cosine functions related to the Pythagorean theorem?

The Pythagorean theorem states that in a right triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the other two sides. In the case of sine and cosine functions, the sum of the squares of these two functions at any given point is equal to 1, which satisfies the Pythagorean theorem. This relationship is used in various mathematical applications, such as finding the length of a diagonal in a rectangular coordinate system.

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