$ \sin^2 rac{\pi}{2} = 1 $, $ \cos^2(2 \cdot rac{\pi}{2}) = \cos^2 \pi = (-1)^2 = 1 $, so $ f = 1 + 1 = 2 $? No — wait:

Sun, 03 May 2026 08:06:44 +0000

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