Question

вспоминаю тригонометрию

Answer 1

$sqrt{3}(1-2cos^215^o)= sqrt{3}(sin^215^o+ cos^215^o- 2cos^215^o)=\ = sqrt{3}(sin^215^o-cos^215^o)=-sqrt{3}(cos^215^o-sin^215^o)=\ =-sqrt{3}*cos(2*15^o)=-sqrt{3}*cos30^o=- sqrt{3} * frac{ sqrt{3} }{2} =-1,5$