Question

срочно решите, оч надо

Answer 1

$1)Cosalpha=Cos^{2}frac{alpha}{2}-Sin^{2}frac{alpha}{2}\\Cosalpha=2Cos^{2}frac{alpha}{2}-1\\Cosalpha=1-2Sin^{2}frac{alpha}{2}$

$2)Sin3alpha=2Sinfrac{3alpha}{2}Cosfrac{alpha}{2}$

$3)tgfrac{alpha}{2}=frac{2tgfrac{alpha}{4}}{1-tg^{2}frac{alpha}{4}} \\4)Cos8alpha=Cos^{2}4alpha-Sin^{2}4alpha\\Cos8alpha=2Cos^{2}4alpha-1\\Cos8alpha=1-2Sin^{2}4alpha$

$5)Sin(2x-frac{pi}{6})=2Sin(x-frac{pi}{12})Cos(x-frac{pi}{12})\\6)tg7alpha=frac{2tg3,5alpha}{1-tg^{2}3,5alpha}\\7)Sin(alpha-beta)=2Sinfrac{alpha-beta}{2}Cosfrac{alpha-beta }{2}\\8)tg3=frac{2tg1,5}{1-tg^{2}1,5 }$