ТРИГОНОМЕТРИЯ 2cos(α-2π)-sin(α-π/2) ------------------------------ cos(9π/2)+2sin(2π-α)

Question

ТРИГОНОМЕТРИЯ
2cos(α-2π)-sin(α-π/2)
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cos(9π/2)+2sin(2π-α)

Comments

А нет ли там а у 9п/2?

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верно, (9π/2)-а

Answer 1

Cos(α+2π)=cosα,
sin(αα α-π/2)=-sin(π/2 -α) = -cosα.
2cosα-(-cosα)=3cosα -  это числитель.
cos(9π/2 -α) =cos(4π + π/2 -α)= cos(π/2  -α) = sinα.
sin(2π-α) = sin(-α) = -sinα,
sinα+2(-sinα) = -sinα -это знаменатель.
3cosα / (-sinα) = -3 ctgα.