Question

Алгебра, 10
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Answer 1

Ответ:

$\\ \frac{5 \cos(78) }{ \cos(6) \cos(84) } = \frac{5 \cos(90 - 12) }{ \cos(6) \cos(84) } = \frac{5 \sin(12) }{ \cos(6) \cos(84) } = \frac{5 \times 2 \sin(6) \cos(6) }{ \cos(6) \cos(84) } = \frac{5 \times 2 \sin(90 - 84) }{ \cos(84) } = \frac{5 \times 2 \cos(84) }{ \cos(84) } = 5 \times 2 = 10$

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Answer 2

Ответ:

5cos 78⁰ 5cos(90°-12°)

_________= _____________=

cos6⁰ cos84⁰ cos(6°)cos(84°)

5sin(12°) 5×2sin(90°-84°)

=_________ =______________

cos (6°)cos(84°) cos(6°)cos(84°)

5×2cos(84°)

=____________= 5×2=10

cos(84°)