Question

1/tg(368) + 2sin(2550)*cos(-188)/2cos(638)+cos(98) =
Решите пожалуйста!

Answer 1

$\frac{1}{tg368}+\frac{2sin2550\cdot cos(-188)}{2cos638+cos98}=\\\\\star \; tg368=tg(360+8)=tg8\\\star \; sin2550=sin(7\cdot 360+30)=sin30=\frac{1}{2}\\\star \; cos(-188)=cos188=cos(180+8)=-cos8\\\star \; cos638=cos(2\cdot 360-82)=cos82=cos(90-8)=sin8\\\star \; cos98=cos(90+8)=-sin8\\\\=\frac{1}{tg8}+\frac{2\cdot \frac{1}{2}\codt (-cos8)}{2sin8-sin8}=ctg8-\frac{cos8}{sin8}=ctg8-ctg8=0$