sinB=√5/5
cosB=2√5/5
sinA=4/5
cosA=2cosB^2-1=3/5
cosC=-cos(A+B)=-cosAcosB+sinAsinB=(-2√5/25)
sinC=sin(A+B)=sinAcosB+sinBcosA=(11√5/25)
b/sinB=c/sinC,b/c=sinB/sinC=(√5/5)/(11√5/25)=5/11
sinB=√5/5
cosB=2√5/5
sinA=4/5
cosA=2cosB^2-1=3/5
cosC=-cos(A+B)=-cosAcosB+sinAsinB=(-2√5/25)
sinC=sin(A+B)=sinAcosB+sinBcosA=(11√5/25)
b/sinB=c/sinC,b/c=sinB/sinC=(√5/5)/(11√5/25)=5/11