Question

помогите срочно!!!!!!!

Answer 1

Ответ:

Объяснение:

sin(a+b)=sinacosb+sinbcosa

sin(a-b)=sinacosb-sinbcosa

cos(a+b)=cosacosb-sinasinb

cos(a-b)=cosacosb+sinasinb

tg(a+b)=(tga+tgb)/(1-tgatgb)

1) sin42°30'cos47°30'+sin47°30'cos42°30'=sin(47°30'+42°30')=sin90°=1

2) cos27°cos18°-sin27°sin18°=cos(27°+18°)=cos45°=√2/2

3) sin(2π/5)cos(π/15)-cos(2π/5)sin(π/15)=sin((2π/5)-(π/15))=sinπ/3=√3/2

4) cos(4π/9)cos(5π/18)-sin(4π/9)sin(5π/18)°=cos((4π/9)-(5π/18))=cosπ/6=√3/2

5) tg(7π/8)+tg(π/8))/(1-tg(7π/8)tg(π/8))=tg(7π/8+π/8)=tgπ=0