cos pi/12 * cos 5pi/12 + sin 5pi/12 * sin pi/12

cos pi/12 * cos 5pi/12 + sin 5pi/12 * sin pi/12
cos(π/12) * cos(5π/12) + sin(5π/12) * sin(π/12)
Using the cosine addition formula: cos(A - B) = cos(A) * cos(B) + sin(A) * sin(B)

This simplifies to:
cos(π/12 - 5π/12) = cos(-4π/12) = cos(-π/3)

Since cos is an even function:
cos(-π/3) = cos(π/3) = 1/2

Therefore, the result is:
1/2

Тэги:

#cos_pi/12_*_cos_5pi/12_+_sin_5pi/12_*_sin_pi/12

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