Question

cos(30градусов+альфа)-cos(30градусов-альфа)

Answer 1

$cos(30^{circ}+alpha)-cos(30^{circ}-alpha)=\\=cos30^{circ}cosalpha-sin30^{circ}sinalpha-(cos30^{circ}cosalpha+sin30^{circ}sinalpha)=\\=frac{sqrt{3} }{2}cosalpha-frac{1}{2}sinalpha-(frac{sqrt{3} }{2}sinalpha+frac{1}{2}sinalpha)=frac{sqrt{3}cosalpha-sinalpha-sqrt{3}cosalpha-sinalpha }{2}=\\=frac{-2sinalpha}{2}=-sinalpha$

Answer 2

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