$$\sin^2(4) + \sin^2(8) + \sin^2(12) + ... + \sin^2(176)$$
Where the number is in degrees not radians.
$$\cos(x) = \sin(90 - x) \implies \cos(x) = \sin(90 + x)$$
$$\implies \sin(x) = \cos(x - 90)$$
$$S = \sum_{n=1}^{44} \sin^2(4n)$$
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