Created on 2024-06-20Asked by Levi Anderson (Solvelet student)
Show that the functions sin(nπx) and cos(mπx) are orthogonal on the interval [0,1].
Solution
To show that sin(nπx) and cos(mπx) are orthogonal on the interval [0,1]: 1. Compute the inner product: ∫01sin(nπx)cos(mπx)dx. 2. Use the product-to-sum identities: sin(nπx)cos(mπx)=21[sin((n+m)πx)+sin((n−m)πx)]. 3. Integrate: ∫0121[sin((n+m)πx)+sin((n−m)πx)]dx=21[∫01sin((n+m)πx)dx+∫01sin((n−m)πx)dx]. 4. Evaluate the integrals: ∫01sin((n+m)πx)dx=[−(n+m)πcos((n+m)πx)]01=0,∫01sin((n−m)πx)dx=[−(n−m)πcos((n−m)πx)]01=0. Therefore, the inner product is zero, proving that sin(nπx) and cos(mπx) are orthogonal on the interval [0,1]. Solved on Solvelet with Basic AI Model
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DefinitionOrthogonal functions are functions that over the given interval, if we multiply them together and integrate on the interval, the result will be zero. They are the foundation of function spaces and appear in Fourier series, among related expansions. Case: The sine and cosine functions are orthogonal on [0,2π].