Question

Помогите с решением,,,,,,,

Answer 1

$1)14Sinfrac{7pi }{12}*Cosfrac{7pi }{12} =7*(2Sinfrac{7pi }{12}Cosfrac{7pi }{12})=7*Sin(2*frac{7pi }{12})=7Sinfrac{7pi }{6}=7Sin(pi +frac{pi }{6})=7*(-Sinfrac{pi }{6})=7*(-frac{1}{2})=-3,5$

$2)8sqrt{3}Cos^{2} frac{7pi }{12}-8sqrt{3}Sin^{2}frac{7pi }{12}=8sqrt{3}(Cos^{2}frac{7pi }{12} -Sin^{2}frac{7pi }{12})=8sqrt{3}Cos(2*frac{7pi }{12})=8sqrt{3}Cosfrac{7pi }{6}=8sqrt{3}Cos(pi+frac{pi }{6})=8sqrt{3}*(-Cosfrac{pi }{6})=-8sqrt{3}*frac{sqrt{3} }{2}=-12$