(1) f(0)=sin0+sintcos0+1=9/5
sint=4/5
∵t为钝角
∴cost=-√[1-(sint)^2]=-3/5
sin2t=2sintcost=-24/25
f(t)=sin2t+sintcost+1
=-24/25+4/5*(-3/5)+1
=-11/25
(2) b/a=sinB/sinA
b=8*sin30°/sint=8*1/2/(4/5)=5
(1) f(0)=sin0+sintcos0+1=9/5
sint=4/5
∵t为钝角
∴cost=-√[1-(sint)^2]=-3/5
sin2t=2sintcost=-24/25
f(t)=sin2t+sintcost+1
=-24/25+4/5*(-3/5)+1
=-11/25
(2) b/a=sinB/sinA
b=8*sin30°/sint=8*1/2/(4/5)=5