Question

задания в прикреплены

Answer 1

458.

$tg(a+b)=\frac{tga+tgb}{1-tgatgb}=\frac{\frac{4}{3}+\frac{1}{4}}{1-\frac{4*1}{3*4}}=\frac{19}{8}.$

 

439.

$\ \sqrt{2}sin(\frac{\pi}{4}+a)-cosa=cosa+sina-cosa=sina.$

б) $\sqrt{2}sin(a-\frac{\pi}{4})-sina=sina-cosa-sina=-cosa.$

в) $2cos(\frac{\pi}{3}-a)-\sqrt{3}sina=cosa+\sqrt{3}sina-\sqrt{3}sina=cosa.$

г) $\sqrt{3}cosa-2cos(a-\frac{\pi}{6})=\sqrt{3}cosa-\sqrt{3}cosa-sina=-sina.$

 

445.

а) $cos18cos63+sin18sin63=cos(18-63)=cos45=\ \frac{\sqrt{2}}{2}.$

б) cos32cos58-sin32sin58=$cos32cos58-sin32sin58=cos(32+58)=cos90=\ 0.$