Question

2;3;4буду благодарен

Answer 1

$2^o\2cos^23alpha tg3alpha=5cos^23alphacdotfrac{sin3alpha}{cos3alpha}=5cos3alphasin3alpha=2,5cdotsin6alpha\\3.\sin^2alpha+cos^alpha=1Rightarrowcosalpha=sqrt{1-sin^2alpha}\cosalpha=sqrt{1-0,64}=sqrt{0,36}=pm0,6\fracpi2<alphapiRightarrowcosalpha<0\cosalpha=-0,6$

$4.\frac{sin(x+45^o)+sin(x-45^o)}{sin(x+45^o)-sin(x-45^o)}=frac{sin xcos45^o+cos xsin45^o+sin xcos45^o-cos xsin45^o}{sin xcos45^o+cos xsin45^o-sin xcos45^o+cos xsin45^o}=\=frac{2sin xcos45^o}{2cos xsin45^o}=frac{sqrt2sin x}{sqrt2cos x}=tgx$