View source for Relationship between spherical Bessel y and cosine

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<strong>[[Relationship between spherical Bessel y sub nu and cosine|Theorem]]:</strong> The following formula holds for non-negative integers $n$:
$$y_n(z)=(-1)^{n+1}z^n \left( \dfrac{1}{z} \dfrac{d}{dz} \right)^n \left( \dfrac{\cos z}{z} \right),$$
where $y_n$ denotes the [[Spherical Bessel y sub nu|spherical Bessel function of the second kind]] and $\cos$ denotes the [[cosine]] function.
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<strong>Proof:</strong> █ 
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