Question

вычислите 4√3cos(-870°)
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Answer 1

$4 sqrt{3} cos( - 870°) = 4 sqrt{3} cos(870°) = 4 sqrt{3} cos(9 times 90° + 60°) = \ = 4 sqrt{3} cos(60° + 90°) = - 4 sqrt{3} sin(60°) = - 4 sqrt{3} times frac{ sqrt{3} }{2} = - 6$

Ответ: -6.