Question

дано: cosa=0.6; 0<a<90. Найдите sin(a+30)

Answer 1

$0^o<a<90^o$:

$sin a=sqrt{1-cos^2 a}=sqrt{1-0.6^2}=sqrt{0.64}=0.8;\\sin(a+30^o)=sin a*cos 30^o+sin30^o*cos a=\\0.8*frac{sqrt{3}}{2}+0.5*0.6=0.4sqrt{3}+0.3$