The Fourier series of a real periodic function has onlyP. cosine terms...
Because sine function is odd and cosine is even function.
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The Fourier series of a real periodic function has onlyP. cosine terms...
Fourier Series of Real Periodic Function
Fourier series is a mathematical technique to represent a periodic function as a sum of sine and cosine terms. The Fourier series of a real periodic function f(x) is given by:
f(x) = a0/2 + Σ(an*cos(nωx) + bn*sin(nωx))
where ω = 2π/T is the angular frequency, T is the period of the function, and an and bn are the Fourier coefficients given by:
an = (2/T) ∫f(x)cos(nωx)dx
bn = (2/T) ∫f(x)sin(nωx)dx
Even and Odd Functions
A function f(x) is said to be even if f(-x) = f(x) for all x, i.e., it is symmetric about the y-axis. Examples of even functions are cos(x), x², |x|, etc.
A function f(x) is said to be odd if f(-x) = -f(x) for all x, i.e., it is symmetric about the origin. Examples of odd functions are sin(x), x³, etc.
Cosine and Sine Terms in Fourier Series
If a function f(x) is even, then its Fourier series contains only cosine terms and no sine terms. This is because the integral of an odd function over a symmetric interval is zero, and hence the bn coefficients vanish.
Similarly, if a function f(x) is odd, then its Fourier series contains only sine terms and no cosine terms. This is because the integral of an even function over a symmetric interval is zero, and hence the an coefficients vanish.
Answer
From the above discussion, we can conclude that:
- The Fourier series of a real periodic function has only cosine terms if it is even
- The Fourier series of a real periodic function has only sine terms if it is odd
Therefore, the correct answer is option 'A', i.e., the Fourier series of a real periodic function has only cosine terms if it is even and sine terms if it is odd.
The Fourier series of a real periodic function has onlyP. cosine terms...
A
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